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Chapter 6 Review
More Questions

1. Use the table below to find the average acceleration of the car from time t=20 to t=22. Answer: 6.0 m/s2

time (s)
car's velocity (m/s)
20
6
21
12
22
18
23
24
24
30

2. Use the velocity-time graph below to
(a) estimate the average acceleration between time t=4 and t=9. Answer: 1.8 m/s2
(b) estimate the instant acceleration at time t=3.Answer: 2.7m/s2

3. A plane with a velocity of 94 m/s is accelerated uniformly at a rate of 4.0 m/s2 for 3.4s. What is the plane's final velocity? Answer: 110m/s

4. A car traveling at a speed of 25 m/s brakes at a uniform -4.0 m/s2 for 6.0s. How far does the car travel during that time? Answer: 78 m

5. An airplane with a velocity of 32 m/s needs to reach a velocity of 78 m/s for takeoff. If there is only 0.60 km of unway left, what must the constant acceleration be? Answer: 4.2 m/s2

6. A feather is falling at a constant velocity of 4.0 m/s. As the feather passes a ledge that is 78.4 hight a rock is dropped from the ledge.
a) How far below the ledge will the feather be when the rock reaches the ground? Answer: 16 m
b) How high is the cliff? Answer: 39 m/s

7. A bullet is fired straight up with an initial velocity of 109 m/s. It passes the top of a cliff with a velocity of 55.1 m/s.
a) When the bullet passes the top of the cliff, how long has it been since it was firts? Answer: 5.50 m
b) How high is the cliff? Answer: 451 m

8. After making a delivery, a truck driver must maneuver the vehicle backwards down a narrow ramp. The speed of the truck increases with distance down the ramp. Describe the truck's acceleration.
Answer: Because the truck's velocity is backward, or negative, the acceleration is also negative even though the truck's speed is increasing.

9. How can you find the instantaneous acceleration of an object whose curve on the velocity-time graph is a straight line?
Answer: The instantaneous acceleration is the slope of the curve on such a graph

10. Suppose an object starts at rest. Explain how the displacement of the object, which has a constant acceleration, can be determined from a velocity-time graph.
Answer: The displacement is the area under the curve on such a graph. The curve in this case is a straight line. The triangular area under the curve equals the displacement of the object.

11. Describe the curve on a position-time graph of an object with a constant velocity. How does the curve differ for an object with a constant velocity. How does the curve differ for an object that is accelerating constantly?
Answer: For an object with a constant velocity, the curve is a straight line. For an accelerating object, the curve is half of a parabola.

12. Derive an equation for determining displacement when velocity and acceleration are known.
Answer: By using d=1/2(vf +vi) and (vf-vi)/a=t and substituting the second equation into the first, displacement can be calculated using the equation: d= (v2f - v2i)/2a.

13. How is the acceleration of an object in free fall related to acceleration due to gravity?
Answer: For an object in freefall, a=g.

14. In your own words, state the first and last steps that are critical to solving any physics problem.
Answer: The problem must first be carefully read and analyzed. Making a sketch could be helpful. Once the problem is solved systematically, the answer should be evaluated to determine whether or not the numerical value is reasonable.

 

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