A rock is dropped (from rest) off a bridge over the Merrimack River. The falling rock
accelerates at 10 m/s2 downward. If it takes 2.5 seconds before a splash is heard,
approximately how high is the bridge?

Answers

Answer 1

Answer:

31.25 meters or ~31 meters approximately

Explanation:

Let's see which of the 5 variables we are given since this is a constant acceleration problem.

[tex]v_i \ \ \ \ \ \ t \\ v_f \ \ \ \ \ \triangle x \\ a[/tex]

We want to find the height of the bridge, aka the vertical displacement of the rock. Let's set the upwards direction to be positive and the downwards direction to be negative.

We are told that the acceleration is 10 m/s² downward, so we have a = -10 m/s².

We are also told that the time it takes the rock to hit the water is 2.5 seconds. Time is the same regardless of the x- or y- direction, so we can say that t = 2.5 seconds.

Now, we aren't told this directly, but we can figure out that the velocity in the y-direction is 0 m/s, since the rock is dropped from rest off the bridge. Therefore, [tex]v_i=0 \frac{m}{s}[/tex].

We want to find the vertical displacement, the height of the bridge, so we can say that [tex]\triangle x= \ ?[/tex]

We have 4 out of 5 variables:

[tex]v_i,\ a, \ t, \ \triangle x[/tex]

Look through the constant acceleration equations to see which equation has all 4 of these variables. You should come up with this one (no final velocity):

[tex]x_f=x_i+v_it+\frac{1}{2}at^2[/tex]

Subtract [tex]x_i[/tex] from both sides of the equation to get:

[tex]\triangle x=v_it+\frac{1}{2}at^2[/tex]

Substitute in our known variables and solve for delta x.

[tex]\triangle x=(0\frac{m}{s})(2.5s) + \frac{1}{2} (-10\frac{m}{s^2})(2.5s)^2[/tex]

0 m/s multiplied by 2.5 s is 0, so we have:

[tex]\triangle x =\frac{1}{2} (-10)(2.5)^2[/tex]

Evaluate the exponent first and multiply the terms together.

[tex]\triangle x =(-5)(6.25)[/tex] [tex]\triangle x =-31.25[/tex]

The vertical displacement is -31.25 meters from the rock's starting position, so we can say that the height of the bridge is 31.25 meters, which is approximately 31 meters tall.

Answer 2

Answer:

31 meters

hope it help you

thanks for free points.........


Related Questions

1. The unit of power is called a derived unit, why?

Answers

Answer:

Because its depends upon fundamental units and formed by combination of two or more fundamental units.

2. Two people, one on Earth and the other on the Moon, try and lift 200 kg blocks. Which person
will have to exert more force to lift their block or will they need to exert the same amount of
force? Explain your reasoning(4 pts)

Answers

Answer:

The person on Earth will have to exert more force to lift their block

Explanation:

The mass of the blocks to be lifted = 200 kg

The location of the first person = On Earth

The location of the second person = On the Moon

The force a person will have to exert to lift the block = The weight of the block = The gravitational force, F, on the block which is given as follows;

[tex]F = \dfrac{G \times M_1}{R^2} \times m_2[/tex]

Where;

[tex]\dfrac{G \times M_1}{R^2}[/tex]= The acceleration due to gravity on the Earth or the Moon, depending on the location of the block

m₂ = The mass of the block

Therefore, given that the acceleration due to gravity on the Earth is larger than the acceleration due to gravity on the Moon, the weight of the block on the Earth is larger than the weight of the block on the Moon, and the person on Earth have to exert more force to lift the heavier weight of the block on Earth than the person on the Moon will have to exert to lift the same block as the block has a lower weight on the Moon due to lower acceleration due to gravity on the Moon.

Help plz will give brainliest

Answers

Answer:

The forces acting on the root beer is the ice cream. This means that the 'air' in the ice cream keeps it at the top of the root beer enabling it to float right at the top.

How much does a 3.0 kg bag of bolts weigh?

A) 7.2 N

B) 14.4 N

C) 22.8 N

D) 29.4 N

E) 58.8 N

Answers

Answer:

29.4N is a 3.0kg bag of bolts weigh.

The force by gravitation is called the weight of a body. The weight of the body with a mass of 3 Kg is 29.4 N.

What is gravitational force?

Gravitational force is a kind of force by which an object attracts other objects into its center of mass. Earth attracts every objects into its center and thereby we are all standing on the surface.

Gravitational force is acting downward on a body and it depends on the mass of the body. Greater the mass, greater will be the fore of gravitation and its weight experienced on earth.

Given that, mass of the bag = 3 Kg.

force by gravitation  = Mg = 3 × 9.8 m/s² = 29.4 N.

where, g is the acceleration due to gravity. Therefore, the weight of the bag is 29.4 N. Hence, option D is correct.

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What is called gravitational potential energy?

Answers

Answer:

Potential gravitational energy is the energy that the body has due to the Earth's gravitational attraction. In this way, the potential gravitational energy depends on the position of the body in relation to a reference level.

Explanation:

3
A comb is charged negatively when coming a dry hair
is there a tranfer of charge alone or mass also

Answers

Answer:

there is transfer of change alone

Answer:

someone pls explain this question

help me pleaseeeee ​

Answers

How often the particles of a medium vibrate

Answer:

Explanation:

Frequency, in physics, the number of waves that pass a fixed point in unit time; also, the number of cycles or vibrations undergone during one unit of time by a body in periodic motion...............

Intermolecular force is stronger than the kinetic energy in?

Answers

Answer:

If the average kinetic energy is greater than the attractive forces between the particles, a substance will not condense to form a liquid or a solid. If the kinetic energy is less than the attractive forces, a liquid or solid will form.

Explanation:


5.
Assertion (A): Both stretched spring and compressed spring have potential energy
Reason (R): Work is done against the restoring force in each case.
a) Both A and R are true and R is the correct explanation of A
b) Both A and R true and R is not the correct explanation of A
c) A is true but Ris false
d) A is false but R is true​

Answers

Answer:

A. Both A and R are true and R is the correct explanation of A

how can we calculate acceleration in motion which is not uniform or uniformly accelerated​ please help tell me another formula to calculate acceleration

Answers

Answer:

These are some of the ones I found or know of.

Explanation:

F=ma

A= v-u/t

A= v^2/r

Un prisma rectangular de cobre, de base igual a 36 centímetros cuadrados y una altura de 10 cm se sumerge hasta la mitad por medio de un alambre en un recipiente que contiene alcohol ¿que volumen de alcohol desaloja?

Answers

La respuesta correcta es 180 centímetros cúbicos o 180 [tex]cm^{3}[/tex]

Explicación:

El primer paso para saber cuanto alcohol desaloja el prisma es calcular el volumen total del prisma. El volumen se puede encontrar usando la formula V (Volumen) = B (base) x h (altura). El proceso se muestra a continuación:

V  = B x h

V = 36 [tex]cm^{2}[/tex] x 10 cm

V= 360 [tex]cm^{3}[/tex]

Finalmente, el volumen total del prisma debe dividirse en 2 considerando que solo la mitad del prisma fue sumergida y esta mitad equivale al volumen del alcohol desplazado.

360 [tex]cm^{3}[/tex] ÷ 2 = 180 [tex]cm^{3}[/tex]  

El volumen de fluido desplazado es de 180 cm^3.

Sabemos que el objeto va a desplazar su propio volumen de fluido. Por lo tanto, necesitamos obtener el volumen del objeto a, este es el volumen del fluido que eventualmente será desplazado por el sólido.

El volumen del sólido es;

V = 36 cm^2 * 10 cm^2 = 360 cm^3

desde que se sumergió a la mitad, volumen de alcohol desplazado = 360 cm^3/2 = 180cm^3

Obtenga más información sobre el volumen: https://brainly.com/question/7932885

Dorji weight 1500n.if the total surface area of soles of his feet is 0.5 m2 what is the pressure exerted by his body on the ground​

Answers

Answer:

P = 3000 Pa

Explanation:

Weight of Dorji, W = F = mg = 1500 N

The total surface area of soles of his feet is 0.5 m²

We need to find the pressure exerted by his body on the ground​. The pressure is equal to the force acting per unit area. So,

[tex]P=\dfrac{1500\ N}{0.5\ m^2}\\\\=3000\ Pa[/tex]

So, the pressure exerted by his body on the ground​ is 3000 Pa.

By using electroscope, if the body is negatively charged then due to electrostatic induction, then on the leaves there will be appear:
(a) both positive and negative charges
(b) negative charge
(c) positive charge
(d) no charge

Answers

(b) negative charge

This is the answer

it should be

B)Negative charge

Hope this one helped

Which statement describes the interaction between the permanent magnets and the electromagnet in an electric motor? A. The current in the electromagnet is reversed by the permanent magnets B. The current in the permanent magnets is reversed by the electromagnet C. The poles of the permanent magnets are reversed by the electric field of the electromagnet. D. The metal loop in the electromagnet turns because of the magnetic field of the permanent magnets​

Answers

Answer:D

Explanation:AP3X

The statement describes the interaction between the permanent magnets and the electromagnet in an electric motor is option D.

What is magnet?

A substance which is negative charged at one end and positive charged at another end creating the magnetic field around it.

A bar is a magnet which can attract the particle which are charged. It has two poles North and South.

The permanent magnet create magnetic field very strong. The electromagnet is find in the electric motor. In the motor, loop made up of conductor is rotated by the effect of magnetic field of permanent magnet.

Thus, the correct option is D.

Learn more about magnet.

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please help me I need this today

Answers

Answer:

42km/h

Explanation:

Change in km/ Change in time

1.4 x 100

0.033 x100

140km/3.3

= 42.4242 --> 42km/h

Brainliest Appreciated!

The force on the projectile is constant throughout the flight *
True
False

Answers

It’s true for sureeeeeeeee
It’s true of course

What is the astronomical unit used to measure distances in the solar system?

Answers

Answer:

Astronomical unit

Explanation:

Short Answer: It's (au)

Long Answer:

The astronomical unit (au or AU) is defined as exactly 149,597,870,700 meters (about 93 million mi), which is roughly equal to the average distance between the Sun and Earth.

what is the motion of a car​

Answers

Answer: Assuming you are driving a car on the road, consider the motion of the car. As the wheels of the car spin backwards, they push the road backwards. In consequence, the road must push the wheels forward according to the third law of motion. It is this reaction force acting on the wheels causes the car to move forward.

Explanation: hope this helps!

the photos below show four pairs of objects. which pair of objects is experiencing the greatest gravitational force.A. the person and dog B. The person and the ball C. the person and earth D. the person and the building

Answers

Answer:

C.

Explanation:

the earth has a high greavitational pull

Answer: C the person and earth

Explanation: I just answered it on a p e x

OC -5.9 m/s
2. A driver of a car traveling at 15.0 m/s applies the brakes, causing a
uniform acceleration of -2.0 m/s". How long does it take the car to
accelerate to a final speed of 10.0 m/s?​

Answers

Answer:

2.5 s

Explanation:

The formula for acceleration is ;

a= v₂-v₁ / t

where ;

a= acceleration = -2 m/s²

v₂= final velocity = 10 m/s

v₁ = initial velocity = 15 m/s

t= time taken for the car to accelerate = ?

Applying the values in the formula as;

a= v₂-v₁ / t

-2 = 10 - 15 / t

-2t = -5

t= -5/ -2

t= 5/2 = 2.5 s

You are a medical student who has been instructed to make a transverse Cut through the abdomen.Calling through the abdomen in which direction will accomplish your goal

Answers

cutting across the middle of the abdomen from left to right would be a transverse cut

Liam wants to determine if foam is a good insulator. He decides to connect wires to two ends of a battery and then connect one wire to each end of a foam cup. Which inquiry skill is Liam using?

Answers

Answer: liain is using lucid mode

Explanation:btw im from canida so sorry if its wrong

If you walk 6mph how far would you get in 10 seconds?

Answers

Answer:

0.017

Explanation:

6÷3600×10=

6÷360=0.00166666666

=0.017(rounded)

Answer:

The answer is 1 mile in 10 minutes

Explain the difference between mass and weight and
how they are measured.

Answers

Answer:

Mass is a measure of how much force it will take to change that path. Mass depends on how much matter – atoms and so on – there is in an object; more mass means more inertia, as there is more to get moving. ... Weight, on the other hand, is a measure of the amount of downwards force that gravity exerts on an object

The radius of Mars is 3397 km; and its mass is 6.42x10²³ kg. What is the acceleration due to gravity at an altitude of 485 km above the surface of Mars?

Answers

Answer:nfeergnjknrtgrth

Explanation:

Answer:

F = GMm/r^2

MA = GMm/r^2

A = GM/r^2

A = (6.67 * 10^-11)(6.42 * 10^23) / (3.37 * 10^6)^2

A = 3.77 m/s^2

Explanation:

WHOEVER RESPONDS TO THIS FIRST WILL GET BRAINIEST!!!!!!
What is the velocity of a car going 4miles in 30 seconds, with the displacement of 36?

Answers

Answer:

alright i responded

Explanation:

you didnt say i had to answer

Yes I responded to the answer is 47

Which statement correctly describes the charge of the nucleus and the charge of the electron cloud of an atom?

Answers

Answer:

This question is incomplete

Explanation:

This question is incomplete because of the absence of options. However, the charge of a nucleus was discovered by Ernest Rutherford. The nucleus is located in the centre of an atom and it contains protons and neutrons. The protons are positively charged while the neutrons have no charge, thus the charge of the nucleus is positive because the neutrality of the neutron does not affect the charge of the proton.

The charge of an electron was first measured by Robert Millikan. Electrons are negatively charged subatomic particles that balance out the positive charge of the protons.

A ball is dropped from a height of 50 meters above the ground. What is its velocity the moment it hits the ground?

Answers

Answer:

The distance is 45m. (s)

Acceleration is 9.8 m/s^2 (acceleration due to gravity). (a)

We have to find the time (t)

By the 3rd equation of motion,

s = ut + 1/2 at^2 (here u is the initial velocity of the ball)

Since the initial velocity was 0 m/s, the formula becomes s = 1/2 at^2.

(substituting the values in the formula)

45 = 1/2 x 9.8 x t^2

45 = 9.8/2 x t^2

45 = 4.9 x t^2 (9.8/2 = 4.9)

(divide 4.9 on both sides)

45/4.9 = 4.9 x t^2 / 4.9

9.1836 = t^2

3.030 = t

So it takes approximately 3 seconds for the ball to reach the surface of the earth (neglecting air resistance). You can try the same with 50 m .

The velocity of the ball the moment it hits the ground is equal to 31.3 m/s.

What is the equation of motion?

Equation of motion has established a relation between the velocity of the body and acceleration of the body when the body is moving with uniform acceleration along a straight line. The distance traveled in a specific time has expressed a set of equations termed equations of motion.

The first equation of motion can be expressed as follows:

v = u + at

The second equation of motion can be expressed as follows:

S= ut + (1/2)at²

Where u is the initial velocity of a body, v is the final velocity, S is the distance, a is the acceleration and t is the time.

Given, the distance traveled by the ball, S = 50 m

and, the initial velocity of the ball, u = 0 as ball is at rest initially.

From the second equation of motion, find the value of 't':

50 = (0) t + (1/2)× (9.8) ×(t²)

t = 3.19 sec

Now from the first equation of motion, find the value of the final velocity of the ball:

v = (0) + (9.8) (3.19)

v = 31.3 m/s

Therefore, the ball hits the ground with a velocity of 31/3 m/s.

Learn more about the equation of motion, here:

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A platinan bar measure 5.0cm long, 40cm
wide and 1.5 cm thick. if has a mass of 700.0grams.

Calculate the volume of platinum bar.


I need help :( Plz help me​

Answers

Answer:

that is what I got for my answer

Explanation:

I Calculate it and I got 1600

State one way to decrease the moment of a given force about a given axis of rotation.​

Answers

Answer:

The moment of a given force about a given axis of rotation can be decreased by decreasing the perpendicular distance of force from the axis of rotation.

Answer:

hope it helps...

Explanation:

The moment of a given force about a given axis of rotation can be decreased by decreasing the perpendicular distance of force from the axis of rotation.

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