1 A car travels in a circle with constant speed. Which of the following is true?
ID: 1369147 • Letter: 1
Question
1 A car travels in a circle with constant speed. Which of the following is true?
a The net force on the car is zero because the car is not accelerating.
b The net force on the car is directed forward, in the direction of travel.
c The net force on the car is directed inward, toward the center of the curve.
d The net force on the car is directed outward, away from the center of the curve.
2 A job is done slowly, and an identical job is done quickly. Which of the following is true?
a They require the same amount of force, but different amounts of work.
b They require the same amount of work, but different amounts of power.
c They require the same amounts of power, but different amounts of work.
d They require the same amounts of work, but different amounts of energy.
3 How many joules of work are done on a box when a force of 60 N pushes it 5 m in 3 seconds?
1 300 J
2 12 J
3 100 J
4 36 J
4 J
4 A 1 kg cart moving with a speed of 3 m/s collides with a 2 kg cart at rest. If the carts stick together after the collision, with what speed will they move after the collision?
a 3 m/s
b 1.5 m/s
c 1 m/s
d 2 m/s
Explanation / Answer
1) as the car is travelling in a circle ,
as centripetal acceleration is needed to move in a circle
c The net force on the car is directed inward, toward the center of the curve.
2)
for the same job , the amount of energy needed is same
b They require the same amount of work, but different amounts of power.
3)
work done = force * distance
work done = 60 * 5
work done = 1) 300 J
4)
let the final speed is v
Using consevration of momentum
1 * 3 + 2 * 0 = (1 + 2) * v
v = 1 m/s
the speed after collision is c) 1 m/s
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