Answer:
It is a form of mechanical energy
Explanation:
5. How does a jack make changing a tire easier?
Answer: An jack makes changing a tire easier because it lifts up the car to get the tire off of the ground.
Explanation:
pls help giving brainliest!
• Explain how Ohm's Law is like a river.
o What represents Voltage?
o What represents Current?
o What represents Resistance?
Answer:
Pressure of water = Voltage
Flow rate of water = Current
Obstructions present in the river = Resistance
Explanation:
We can describe Ohm's Law by using the river analogy,
The flow of water from a mountain to lower parts can be considered as change from high potential to a lower potential.The flow of water can also be considered as flow of electrons, that is current in a circuitThere are also obstructions in rivers that can be considered as resistance in an electric circuit.A swift blow with the hand can break a pine board. As the hand hits the board, the kinetic energy of the hand is trans- formed into elastic potential energy of the bending board, if the board bends far enough, it breaks. Applying a force to the center of a particular pine board deflects the center of the board by a distance that increases in proportion to the fore. Ultimately the board breaks at an applied force of 800 N and a deflection of 1.2 cm.
a. To break the board with a blow from the hand, how fast must the hand be moving? Use 0.50 kg for the mass of the hand.
b. If the hand is moving this fast and comes to rest in a dis- tance of 1.2 cm, what is the average force on the hand?
(a) The velocity is "6.2 m/s".
(b) The average force is "800.83 N".
According to the question,
Force,
F = 800 NDeflection,
x = 1.2 cm= [tex]1.2\times 10^{-2} \ m[/tex]
As we know,
The work done,
→ [tex]W = F\times d[/tex]
[tex]= 800\times 1.2\times 10^{-2}[/tex]
[tex]= 9.6 \ J[/tex]
(a)
Given:
Mass of hand,
m = 0.50 kgNow,
→ [tex]\frac{1}{2} mv^2 = 9.6 \ J[/tex]
[tex]v = \sqrt{\frac{2\times 9.6}{0.50} }[/tex]
[tex]= 6.2 \ m/s[/tex]
(b)
→ [tex]v^2 = u^2 +2ax[/tex]
→ [tex]a= \frac{v^2}{2x}[/tex]
[tex]= \frac{(6.2)^2}{2\times 1.2\times 10^{-2}}[/tex]
[tex]= 1601.67 \ m/s^2[/tex]
hence,
The average force will be:
→ [tex]F_{avg} = m\times a[/tex]
[tex]= 0.50\times 1601.67[/tex]
[tex]= 800.83 \ N[/tex]
Thus the above answers are correct.
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imagine a single charge creating an electric field. what is the relationship between electric field strength and the distance from the charge?
a. direct
b. inverse
c. inverse squared
d. indirect
Answer:
b. inverse
Explanation:
[tex]E = \frac{V}{d} \\ d \: is \: the \: distance \\ [/tex]
mathematical expression between wave number and frequency
state and explain newton second law of motion also describe the concept of force, represent it quantiatively and derive the unit of force
this is a long question only answer if you know how to solve it you will be REWARDED with points
Explanation:
Newton's second law of motion states F=ma which means force is equal to mass multiplied by acceleration which in simple terms means If you give mass force it will accelerate the concept of force in physics is any interaction that when unopposed will change the motion of an object.
At what rate is work done if the 250 Newton object from number six is moved into a hot at 4 m in four seconds
Answer:
250w
Explanation:
W=Fd
W= 250 x 4= 1000J
P=E/t=1000/4s=250w
Tarnish is produced by a redox reaction that occurs when a metal reacts with
a nonmetallic compound. The green tarnish on a copper penny might be
produced by a reaction between copper and hydrogen sulfide. What occurs
during this reaction?
A. Hydrogen sulfide acts as an acid, and copper acts as a base.
B. Copper atoms gain electrons from sulfur atoms.
C. A double-replacement reaction takes place.
D. Copper atoms lose electrons to sulfur atoms.
Answer:
Copper atoms lose electrons to sulfur atoms
Explanation:
a p e x (:
Find the current passing through each of the 3 resistors connected parallel to each other as shown in the figure (i1, i2, I3). Show your actions clearly.
Answer:
I1 = ε/R1
I2 = ε/R2
I3 = ε/R3
Explanation:
From the image, we see that the resistors are connected in parallel. This means that the voltage passing through them is the same.
Now, formula for current is; I = V/R
In this case, V which is voltage is denoted by ε.
Thus;
I1 = ε/R1
I2 = ε/R2
I3 = ε/R3
A sinusoidal electromagnetic wave is propagating in a vacuum in the z-direction. Part A If at a particular instant and at a certain point in space the electric field is in the x-direction and has a magnitude of 4.70 V/mV/m, what is the magnitude of the magnetic field of the wave at this same point in space and instant in time
Answer:
the magnitude of the magnetic field is 1.23 × 10⁻⁸ T { in the +y direction }
Explanation:
Given the data in the question;
the relation between the electric field and the magnetic field in an electromagnetic wave can be written as follows;
c = E₀/B₀
where c is speed of light, E₀ is the amplitude of the electric field and B₀ is the amplitude of the magnetic field.
given that; E₀ = 4.70 V/m, we know that; speed of light c = 3 × 10⁸ m/s
so from our relation; c = E₀/B₀
B₀ = E₀/c
we substitute
B₀ = 4.70 / 3 × 10⁸
B₀ = 1.23 × 10⁻⁸ T { in the +y direction }
Therefore, the magnitude of the magnetic field is 1.23 × 10⁻⁸ T { in the +y direction }
An Olympic skier moving at 20.0 m/s down a 30.0o slope encounters a region of wet snow, of
coefficient of friction μk = 0.740. How far down the slope does she go before stopping?
a.119 m
b.145 m
c.170 m
d.199 m
Answer:
Option B
Explanation:
Forces acting on the skier-
F1 [tex]= -mg sin(30)[/tex] down the slope
F2 [tex]= -mg cos(30)[/tex]
F3 = friction force [tex]= 0.74 mg cos(30)[/tex]
Net force, down the slope
[tex]= -mg sin(30)+ 0.74 mg cos(30)\\= mg(.74 cos(30)-sin(30))\\= 0.14mg\\= 1.38m[/tex]
Acceleration [tex]= F/m= 1.38[/tex] m/s2
Acceleration remains constant, initial speed is 20 m/s
Speed at time t is [tex]1.38t- 20[/tex] m/s
Distance down the slope at time t is [tex]0.69t^2- 20t[/tex]
When the skier stops, her speed is 0. Thus,
, [tex]1.38t- 20= 0\\t= 20/1.38\\= 14.5[/tex] seconds
Distance travelled in 14.5 seconds [tex]= (0.69)(14.52- 20(14.5)= -145 m[/tex](negative because it is down the slope).
Option B is correct
space question 50 points
Explain how sun angle and seasons vary as you move away from the equator.
Seasonal change in the angle of sunlight, caused by the tilt of the Earth's axis, is the basic mechanism that results both in warmth of the weather and in length of the day.
How does clothing and body language affect a job interview?
Answer:
please give me brainlist and follow
Explanation:
Whilst first impressions can be important, your body language during the interview can make or break your overall performance. With experts saying that between 75-90% of communication is non-verbal, it is important to think about what your body is saying about you during an interview.
a ball rolls horizontally of the edge of the cliff at 4 m/s, if the ball lands at a distance of 30 m from the base of the vertical cliff, what is the the hight of the cliff
Answer:
Approximately [tex]281.25\; \rm m[/tex]. (Assuming that the drag on this ball is negligible, and that [tex]g = 10\; \rm m \cdot s^{-2}[/tex].)
Explanation:
Assume that the drag (air friction) on this ball is negligible. Motion of this ball during the descent:
Horizontal: no acceleration, velocity is constant (at [tex]v(\text{horizontal})[/tex] is constant throughout the descent.)Vertical: constant downward acceleration at [tex]g = 10\; \rm m \cdot s^{-2}[/tex], starting at [tex]0\; \rm m \cdot s^{-1}[/tex].The horizontal velocity of this ball is constant during the descent. The horizontal distance that the ball has travelled during the descent is also given: [tex]x(\text{horizontal}) = 30\; \rm m[/tex]. Combine these two quantities to find the duration of this descent:
[tex]\begin{aligned}t &= \frac{x(\text{horizontal})}{v(\text{horizontal})} \\ &= \frac{30\; \rm m}{4\; \rm m \cdot s^{-1}} = 7.5\; \rm s\end{aligned}[/tex].
In other words, the ball in this question start at a vertical velocity of [tex]u = 0\; \rm m \cdot s^{-1}[/tex], accelerated downwards at [tex]g = 10\; \rm m \cdot s^{-2}[/tex], and reached the ground after [tex]t = 7.5\; \rm s[/tex].
Apply the SUVAT equation [tex]\displaystyle x(\text{vertical}) = -\frac{1}{2}\, g \cdot t^{2} + v_0\cdot t[/tex] to find the vertical displacement of this ball.
[tex]\begin{aligned}& x(\text{vertical}) \\[0.5em] &= -\frac{1}{2}\, g \cdot t^{2} + v_0\cdot t\\[0.5em] &= - \frac{1}{2} \times 10\; \rm m \cdot s^{-2} \times (7.5\; \rm s)^{2} \\ & \quad \quad + 0\; \rm m \cdot s^{-1} \times 7.5\; s \\[0.5em] &= -281.25\; \rm m\end{aligned}[/tex].
In other words, the ball is [tex]281.25\; \rm m[/tex] below where it was before the descent (hence the negative sign in front of the number.) The height of this cliff would be [tex]281.25\; \rm m\![/tex].
A 16 Ω resistor and a 6 Ω resistor are connected in series to an ideal 6 V battery.
Find the current in each resistor.
Answer in units of A.
b) Find the potential difference across the first
resistor.
Answer in units of V.
c) Find the potential difference across the second
resistor.
Answer in units of V
Answer:
(a) 0.273 A
(b) 4.368 V
(c) 1.638 V
Explanation:
From the question,
(a) Applying ohm's law
V = IR'...................... Equation 1
Where V = Voltage of the battery, I = Current in each of the resistor, R' = Total resistance of the combined resistors
Since the Two resisstors are connected in series,
(i) The same current flows through both resistors
(ii) The total resistor (R') = R₁+R₂
Therefore,
V = (R₁+R₂)I
Make I the subject of the equation
I = V/(R₁+R₂)................. Equation 2
Given: V = 6 V, R₁ = 16 Ω, R₂ = 6 Ω
Substitute into equation 2
I = 6/(16+6)
I = 6/22
I = 0.273 A
(b) The potential difference across the first resisto
V₁ = IR₁...................... Equation 3
Given: I = 0.273 A, R₁ = 16 Ω
Substitute these values into equation 3
V₁ = 0.273(16)
V₁ = 4.368 V
(c) The Potential difference across the second resistor is
V₂ = IR₂.................... Equation 4
V₂ = 0.273×6
V₂ = 1.638 V
An object is placed in front of a thin converging lens of focal length 12 cm. The image of the object is upright and 2.5 times as tall as the actual object. What is the distance of the object to the lens?
7.2 cm
6.0 cm
4.2 cm
15 cm
The distance of the object to the lens will be a) 7.2 cm
What is focal length?The distance between the convex lens or a concave mirror and the focal point of a lens or mirror is called the focal length. It is the point where parallel rays of light meet or converge.
magnification (m) = h(image )/ h(object ) = image distance / object distance
given
h(image ) = 2.5 * h(object)
m = 2.5 * h(object) / h(object ) = 2.5
2.5 = image distance / object distance
2.5 = v / u
v = 2.5 u
using lens formula
given
focal length (f) = + 12cm
1/v - 1/u = 1/focal length
1/2.5 u - 1/u = 1/12
u = - 7.2 cm
correct option a)7.2 cm
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Visible light falls into wavelength ranges of 400-700 nm, for which 1 m = 1 × 10 9 nm . The energy and wavelength of light are related by the equation E = h c λ where E is energy in Joules, h is Planck's constant ( 6.626 × 10 − 34 J-s ), c is the speed of light ( 2.998 × 10 8 m/s ), and λ is the wavelength in m. If a visible light photon has a wavelength of 560.6 nm, what is the energy of the photon (in J)?
Given the wavelength of the visible light photon, the energy of the photon is 3.54 × 10⁻¹⁹J
Given the data in the question;
Wavelength of visible light; [tex]\lambda = 560.6 nm = 5.606*10^{-7}m[/tex]
Speed of light; [tex]c = 2.998 * 10^8 m/s[/tex]
Planck's constant; [tex]h = 6.626 * 10^{-34} J.s[/tex]
The energy and wavelength of light are related by the equation:
[tex]E = \frac{hc}{\lambda}[/tex]
Where E is energy of photon in Joules, h is Planck's constant, c is the speed of light and λ is the wavelength,
We substitute our given value into the equation
[tex]E = \frac{(6.626*10^{-34}J.s)(2.998*10^8m/s)}{5.606*10^{-7}m} \\\\E = \frac{(1.986*10^{-25}J.m}{5.606*10^{-7}m}\\\\E = 3.54 * 10^{-19}J[/tex]
Therefore, given the wavelength of the visible light photon, the energy of the photon is 3.54 × 10⁻¹⁹J
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Calculate the amount, in grams, of an original 300 gram sample of potassium 40 remaining after 3.9 billion years.
a. 300
b. 150
c. 75
d. 37.5
A graph of a wave is shown if the frequency f is 8.0 Hz what is the waves speed
Answer:
C
[tex]6 = \frac{3}{2} \lambda \\ wavelength : \: \lambda = 4 \: m \\ from \: wave \: equation \\ v = f\lambda \\ v = 8 \times 4 \\ v = 24 \: {ms}^{ - 1} [/tex]
The speed of the waves will be = [tex]24\dfrac{m}{s}[/tex]
Given data is frequency f = 8.0 Hz
What will be the speed of the wave?As we know that the speed of the wave is given by the formula below
[tex]V=f\times \lambda[/tex]
Since
[tex]6=2 \lambda[/tex]
[tex]\lambda =3m[/tex]
now
[tex]V=8\times3[/tex]
[tex]V=24m[/tex]
The speed of the waves will be = [tex]24\dfrac{m}{s}[/tex]
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state the Newton 2nd law of motion and also prove that F= ma
Explanation:
F = ma is the formula of Newton's Second Law of Motion. Newton's Second Law of Motion is defined as Force is equal to the rate of change of momentum. For a constant mass, force equals mass times acceleration.
...
Spiral fracture of bone: Spiral fracture of bone occurs due to twisting of the limb, and is a very common skiing accident. The fracture plane is helical, and is very difficult to heal. Mechanically, it occurs due to an applied torsion load on the bone. Recall that a state of pure shear occurs within the material when torsion is applied on a cylinder, and the bone can be idealized as a cylinder. Let a femur bone be subjected to a torque of T 50 N-m. Assume body weight of the person to be W- 80 Kgs, while each leg is subjected to half of that weight. Given radius of the bone r 10 mm. Compute the principal stresses and shear stresses, as well as orientation of planes on which these stresses are realized.
Answer:
principal stresses :б1 = 32.62mPa б2 = 31.38mPa
Max Shear stress : 16.31 mPa
Orientation of max principle plane = 44.43°
Orientation of minimum principal plane = 134.43°
Explanation:
Given data:
Torque = 50 N-m
weight = 80 kgs
half of weight is subjected to each leg
radius of bone = 10 mm = 0.010 m
a) Determine the principal stresses and shear stress
first calculate the max shear stress ( this will occur in the outermost element
= 16T / π*d^3 where : T = 50 , d = 0.020 m
hence max shear stress = 32 mPa
next determine compressive stress
= ( 40*g) / π/4*d^2 . where : d = 0.020 m , g = 9.81
hence compressive stress = 1.24 mPa
draw and calculate the radius of Mohr's circle
radius of Mohr's circle = 32.0060
Hence principal stresses = 32.0060 ± 0.62
б1 = 32.62mPa
б2 = 31.38mPa
attached below is the remaining part of the solution
if you travel at a constant velocity what happens to the time it takes to travel you need to travel a longer distance ?
9
A canoe with a mass of 120 kg is floating downriver at a speed of 2.5 m/s. What is the canoe's kinetic eergy?
Answer:
K.E. = ½ × mv²
= ½ × 120 × (2.5)²
= 60 × 6.25
= 375 J
After graduation, you face a choice. You can work for a multinational consulting firm and earn a starting salary (including benefits) of $40,000, or you can start your own consulting firm using $5,000 of your own savings. If you keep your money in a savings account, you can earn an interest rate of 7 percent. You choose to start your own consulting firm. At the end of the first year, you add up all of your expenses and revenues. Your expenses include $14,000 for rent, $1,000 for office supplies, $24,000 for labor, and $4,500 for telephone expenses. After operating your consulting firm for a year, your total revenues are $88,000.
Required:
What are your total explicit cost and total implicit costs?
Answer:
Explanation:
Money is used to cover the explicit cost. They're what we're used to seeing, and they're easy to identify. There are several classifications for explicit costs; we can distinguish between fixed and variable costs, as well as direct and indirect costs. Raw materials, manpower, indirect production costs, and so on are all factors that contribute to its expense.
The opportunity cost of using a resource is the amount of money paying for it that might have been used on something else.
Alternative benefit options or money that we miss earning by doing such business acts are referred to as opportunity costs.
When a corporation foregoes an alternative action but does not make a bill, it incurs implicit costs. These are a company's hidden costs:
1. The use of the firm's own funds (money or assets).
2. The owner's capital, savings, and financial services are used.
From the given information:
The total explicit cost = Rent + office supplies + office staff + telephone expense
=$( 14000 + 1000 + 24000 + 4500)
= $43500
The total implicit cost = forgone salary + forgone interest
= $40000 + 7% of $5000
= $40000 + 350
=$40350
What is the change in internal energy if 30 J of heat are released from a
system and the system does 50 J of work on its surroundings?
Use AU= Q-W.
Answer:
Option B. –80 J
Explanation:
From the question given above, the following data were obtained:
Heat (Q) released = –30 J (negative sign because the heat is being released to the surrounding)
Work (W) = 50 J
Change in internal energy (ΔU) =?
We can obtain the change in the internal energy as follow:
ΔU = Q – W
ΔU = –30 – 50
ΔU = –80 J
Therefore, the change in the internal energy is –80 J
Thus, option B gives the correct answer to the question.
Water is to be heated from 10°C to 80°C as it flows through a 2-cm-internal-diameter, 13-m-long tube. The tube is equipped with an electric resistance heater, which provides uniform heating throughout the surface of the tube. The outer surface of the heater is well insulated, so that in steady operation all the heat generated in the heater is transferred to the water in the tube. If the system is to provide hot water at a rate of 5 L/min, determine the power rating of the resistance heater. Also, estimate the inner surface temperature of the pipe at the exit.
Answer:
- the power rating of the resistance heater is 24139.5 W
- the inner surface temperature of the pipe at the exit is 96.34°C
Explanation:
Given the data in the question;
Flow rate of water in the tube V" = 5L/min = 8.333 × 10⁻⁵ m³/s
The water is to be heated from 10°C to 80°C;
so Average or mean temperature [tex]T_{avg[/tex] will be;
[tex]T_{avg[/tex] = (T₁ + T₂) / 2 = (10 + 80) / 2 = 90/2 = 45°C
Now, from the Table " Properties of Water " at average temperature;
at [tex]T_{avg[/tex] = 45°C
density p = 990.1 kg/m³
specific heat [tex]C_p[/tex] = 4180 J/kg-k
thermal conductivity k = 0.637 W/m-°C
Now, we determine the mass flow;
m" = pV"
we substitute
m" = 990.1 × 8.333 × 10⁻⁵
m" = 0.08250 kg/s
we know that the power rating of the resistance heater is equal to the heat transfer rate to the water;
Q' = m"[tex]C_p[/tex]( T₂ - T₁ )
we substitute
Q' = (0.08250 × 4180 ) ( 80 - 10 )
Q' = 344.85 × 70
Q' = 24139.5 W
Hence, the power rating of the resistance heater is 24139.5 W
Next, we determine the average velocity of water in the tube;
[tex]V_{avg[/tex] = V" / [tex]A_c[/tex]
[tex]V_{avg[/tex] = V" / ( [tex]\frac{1}{4}[/tex]πD² )
given that; flows through a 2-cm-internal-diameter; D = 0.02 m
we substitute
[tex]V_{avg[/tex] = (8.333 × 10⁻⁵) / ( [tex]\frac{1}{4}[/tex]π × (0.02)² )
[tex]V_{avg[/tex] = (8.333 × 10⁻⁵) / ( 3.14159 × 10⁻⁴ )
[tex]V_{avg[/tex] = 0.265 m/s
Also, from table " saturated water property table "
At 45°C
viscosity μ = 0.596 × 10⁻³ kg/m-s
Prandtl number Pr = 3.91
Now, we determine the kinematic viscosity
v = μ / p
we substitute
v = ( 0.596 × 10⁻³ ) / 990.1
v = 6.01959 × 10⁻⁷ m²/s
so, Reynolds number in the flow region will be;
Re = ([tex]V_{avg[/tex] × D) / v
we substitute
Re = ( 0.265 × 0.02) / (6.01959 × 10⁻⁷)
Re = 8804.586
we can see that our Reynolds number ( 8804.586 ) more than 2300 and less than 10,000.
Hydraulic and thermal entry length are equal in this flow region,
such that;
[tex]L_h[/tex] = [tex]L_t[/tex]
⇒ 10 × D = 10 × 0.02 = 0.2 m
we can see that the entry length ( 0.2 m ) is smaller than the given length ( 13 m ) in the question; the flow is a turbulent flow.
So we the Nuddelt number
Nu = [tex]0.023Re^{0.8} Pr^{0.4[/tex]
Nu = 0.023 × [tex]8804.586^{0.8[/tex] × [tex]3.91^{0.4[/tex]
Nu = 56.8
Hence, the heat transfer coefficient h will be;
h = [tex]\frac{k}{D}[/tex] × Nu
we substitute
h = [tex]\frac{0.637}{0.02}[/tex] × 56.8
h = 31.85 × 56.8
h = 1809.1 W/m²-°C
Now, area of the heat transfer will be
A[tex]_s[/tex] = πDL
we substitute
A[tex]_s[/tex] = π × 0.02 × 13
A[tex]_s[/tex] = 0.8168 m²
Finally we determine the inner temperature of the pipe at exit. using the relation;
Q' = hA[tex]_s[/tex]( T₃ - T₂ )
we substitute
24139.5 = 1809.1 × 0.8168( T₃ - 10 )
24139.5 = 1477.67288( T₃ - 80 )
24139.5 = 1477.67288T₃ - 118213.8304
24139.5 + 118213.8304 = 1477.67288T₃
1477.67288T₃ = 142353.3304
T₃ = 142353.3304 / 1477.67288T
T₃ = 96.34°C
Therefore, the inner surface temperature of the pipe at the exit is 96.34°C
What is urea? plz help me
Answer:
It is a colorless crystalline compound which is the main nitrogenous breakdown product of protein metabolism in mammals and is excreted in urine.
Answer:
Urea is a compound of nitrogen that is the chief solid substance dissolved in the urine of a mammal and is formed by the breaking down of protein.
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As a woman walks, her entire weight is momentarily placed on one heel of her high-heeled shoes. Calculate the pressure exerted on the floor by the heel if it has an area of 1.45 cm2 and the woman's mass is 53.0 kg. Express the force in N/m2 and lb/in2. (In the early days of commercial flight, women were not allowed to wear high-heeled shoes because aircraft floors were too thin to resist such large pressures.)
Answer:
The correct answer is "517.7 lb/in²".
Explanation:
The given values are:
Woman's mass,
m = 53 kg
Area,
A = 1.45 cm²
= [tex]1.45\times 10^{-4}[/tex] m²
Now,
The weight of woman will be:
⇒ [tex]W=mg[/tex]
On substituting the values, we get
⇒ [tex]=53\times 9.8[/tex]
⇒ [tex]=519.4 \ N[/tex]
Pressure will be:
⇒ [tex]P=\frac{W}{A}[/tex]
⇒ [tex]=\frac{519.4}{1.45\times 10^{-4}}[/tex]
⇒ [tex]=3.57\times 10^6 \ N/m^2[/tex]
or,
⇒ [tex]=3.57\times 10^6 \ Pa[/tex]
As we know,
⇒ 1 pound per sq. inch = 6895 Pascal's
hence,
⇒ [tex]P=\frac{3.57\times 10^6}{6895}[/tex]
⇒ [tex]=517.7 \ lb/in^2[/tex]
a student throws a coin vertically downward frok the top of a building. the coin leaves the throwers hand with a speed of 15.0m/s. what is its speed after falling freely for 2.00s?
Answer:
Final speed after 2 seconds = 34.6 m/s
Explanation:
Given:
Initial speed of coin (u) = 15 m/s
Time taken = 2 seconds
Find:
Final speed after 2 seconds
Computation:
Gravitational acceleration of earth = 9.8 m/s²
Using first equation of motion;
v = u + at
or
v = u + gt
where,
v = final velocity
u = initial velocity
g = Gravitational acceleration
t = time taken
v = 15 + 9.8(2)
v = 15 + 19.6
Final speed after 2 seconds = 34.6 m/s
During the course of a demonstration the professor is called away. When he returns he finds a beaker of water that was at room temperature is now at a slightly higher temperature. There is a stirring rod on the desk and a cigarette lighter. The professor can assume that the temperature increase is due to either heat added or mechanical work done. mechanical work done on the system. heat added to the system.
Answer:
Either heat added or mechanical work done.
Explanation:
Since he found stirring rod on the desk and a cigarette lighter. This means that the beaker was probably either heated with the aid of fire from the lighter.
Also, the stirring rod could have been used to stir the water which will increase the kinetic energy which also means an increase in temperature.
Thus, it's either heat was added or mechanical work was done as a result of stirring.