QUESTION 2 DOK 3 A Thompson's gazelle has a maximum acceleration of 4.5 m/s2 At this acceleration, how much time is required for it to reach a speed of 40 km/h?
Answer:
2.47 s
Explanation:
Convert the final velocity to m/s.
40 km/h → 11.1111 m/sWe have the acceleration of the gazelle, 4.5 m/s².
We can assume the gazelle starts at an initial velocity of 0 m/s in order to determine how much time it requires to reach a final velocity of 11.1111 m/s.
We want to find the time t.
Find the constant acceleration equation that contains all four of these variables.
v = v₀ + atSubstitute the known values into the equation.
11.1111 = 0 + (4.5)t 11.1111 = 4.5t t = 2.469133333The Thompson's gazelle requires a time of 2.47 s to reach a speed of 40 km/h (11.1111 m/s).
A 60 kg swimmer suddenly dives from a 150 kg raft with a speed of 1.5 m/s. The raft is initially at
rest. What is the speed of the raft immediately after the diver jumps if the water has negligible
effect on the raft?
Answer:
v2 = 0.6 m/s in opposite direction
Explanation:
The computation of the speed of the raft is as follows
The center of system mass would be remains at the same place also it has no external force applied
Therefore
V = 0
So,
M1.V1= - (M2.V2)
where,
M1 = 60 kg, V1 = 1.5 m/s
M2 = 150 kg
Now
60 × 1.5 = - 150 × v2
v2 = -0.6 m/s
v2 = 0.6 m/s in opposite direction
The purpose of a cell phone cover is to protect your phone from impact forces. How does a cell phone case do this?
Answer:
the material of the phone case
The purpose of a cell phone cover is to protect your phone from impact forces. It is done by absorbing the impact of force by back cover.
What is Force ?
Force is responsible for the motion of an object. it produces acceleration in the body. According to newton's second law force is mass times acceleration i.e. F =ma. Its SI unit is N which is equivalent to kg.m/s².
The case is made in such a way that, if the cell phone is dropped, the cover will absorb the kinetic energy of the falling phone by the means of deforming without transferring the impact onto the phone.
Cell phone cover is made up of rubber which can restore the forces like a spring. when u apply force to the rubber it get displaced and applied force is stored in the rubber. when cell phone drops, rubber of the cover absorbs the energy of impact. it also provides shied protection to the phone.
Hence this is how cell phone case do this.
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What effect does noise have on different types of signals?
A. It distorts digital signals, making them unreliable.
B. It distorts analog signals, making them unreliable.
C. Noise has no effect on either analog or digital signals.
D. Noise prevents the transmission of both analog and digital
signals.
Answer: it is actually B. :)
Explanation:
Noise can distort analog signals making them unreliable.
What is noise?The random or unwanted signal that mixes up with the original signal is called noise. Noise is an unwanted signal that interferes with the original message signal and causes the message signal's parameters to be corrupted. The message is transformed as a result of this change in the communication process. It's most likely to be inputted at the receiver or channel.Noise can actually bury, distort or cause interference to the analog signal carrying the intelligent information.
What is analog signal?A signal in which a characteristic grows and decreases in lockstep with the object being sent is known as analog signal. The power of the radio wave, for example, rises and falls in accordance with the loudness of the original sound in AM radio.Hence, the correct answer is B.
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A 2.0 kg block is pulled across a horizontal surface by a 15 N force at a constant velocity. What is the force of friction acting on the block?
Answer:
The force of friction acting on the block has a magnitude of 15 N and acts opposite to the applied force.
Explanation:
Net Force
The Second Newton's law states that an object acquires acceleration when an unbalanced net force is applied to it.
The acceleration is proportional to the net force and inversely proportional to the mass of the object.
If the object has zero net force, it won't get accelerated and its velocity will remain constant.
The m=2 kg block is being pulled across a horizontal surface by a force of F=15 N and we are told the block moves at a constant velocity. This means the acceleration is zero and therefore the net force is also zero.
Since there is an external force applied to the box, it must have been balanced by the force of friction, thus the force of friction has the same magnitude acting opposite to the applied force.
The force of friction acting on the block has a magnitude of 15 N opposite to the applied force.
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Answer:
See the explanation.
Explanation:
Q9. Irregular reflection happens when a set of parallel beams are reflected from non-smooth surface which results in non-parallel reflected beams.
Q10.
i) Periscope
ii) There are different types of periscopes but the main characteristic of this instrument is observation over the obstacles or in general objects that are not in the line-of-sight. Basic Periscope uses parallel angled mirrors to project objects that are above the surface in submarines.
Earth travels fastest in January and slowest in July. What is the most likely explanation for this?
A. Earth is nearest the Sun in July and farthest away in January.
B. Earth is nearest the Sun in January and farthest away in July.
C. Earth is nearest the Sun in April and farthest away in October.
D. Earth is nearest the Sun in October and farthest away in April.
Answer:
Earth is nearest the Sun in July and farthest away in July.
Explanation:
Answer:
Correct Answer: B.
Explanation:
Earth is nearest the Sun in January and farthest away in July. Explanation: According to Kepler's Second Law, a planet travels fastest when it is nearest its sun. This means that Earth is actually closest to the Sun in January, when it is winter in the northern hemisphere!
Which item rotates in a magnetic field as an electric motor produces kinetic energy.
A. Lightbulb
B. Loop of wire
C. Battery
D. Permanent magnet
Answer:
Loop of Wire
Explanation: