PROBLEM SET 5 LET’S REVISE

1. A car is travelling at 20 m/s. It accelerates uniformly at 3 m/s2 for 5 s.

a. Sketch a velocity-time graph for the car during the period that it is accelerating.
Include numerical detail on the axes of your graph.

b. Calculate the distance the car travels while it is accelerating.

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2. A sports car accelerates uniformly from rest to 24 m/s in 6 s. Calculate the acceleration
of the car.
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3. Sketch velocity-time graphs for an object; Include numbers and units on the velocity and
time axes in each case.
a. moving with a constant velocity of 6 m/s

b. accelerating uniformly from rest at 2 m/s2 for 10 s.

4. A plane starting from rest accelerates at 3 m/s2 for 25 s. Calculate the increase in velocity
after:
a. 1 s
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b. 5 s
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c. 25 s
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5. Look at the following sketches of velocity-time graphs of moving objects.

In which graph is the object:

a. not accelerating :
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 b. accelerating from rest :
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c. decelerating :
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d. accelerating at the greatest rate :
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6. Sketch a velocity-time graph to show how the velocity of a car travelling along a straight
road changes if it accelerates uniformly from rest for 5 s, travels at a constant velocity for
10 s, then brakes hard to come to rest in 2 s.

7.
a. Plot a velocity-time graph using the data in the following table:

Velocity 0.0 2.5 5.0 7.5 10.0 10.0 10.0 10.0 10.0 10.0
in m/s
Time in s 0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0

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Draw a line of best fit and use your graph to find:
b. the acceleration during the first 4 s
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c. the distance travelled in:
i. the first 4 s of the motion shown
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ii. the last 5 s of the motion shown
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d. the average speed during the 9 seconds of motion shown.
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8. The dripping car from question 7 is still on the road! It is still dripping oil but now at a
rate of one drop per second. The trail of drips is shown on the diagram below as the car
travels from left to right.

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 Describe the motion (the way the car is moving) using the information in this diagram.
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16. A student is investigating the rate of acceleration of a tennis ball rolling down a gently
sloping ramp that is 5 metres long. The student has a stopwatch and a metre rule.

The student decides to measure the average velocity of the tennis ball in two places, A and
B, as it rolls down the slope.
a. Describe the measurements that the student must make to find the velocity in each
place, and how these will be used to find the average velocity in each place.
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b. State what other measurement the student must make to find the acceleration of
the ball. Explain how the student can then calculate the acceleration.
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c. How can the student improve the accuracy of the measurements?

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d. The investigation is more difficult to carry out if the slope is too steep. Explain why
this is so.
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