Review. While learning to drive, you arc in a 1 200-kg car moving at 20.0 m/s across a large, vacant, level parking lot. Suddenly you realize you are heading straight toward the brick sidewall of a large supermarket and are in danger of running into it. The pavement can exert a maximum horizontal force of 7 000 N on the car. (a) Explain why you should expect the force to have a well-defined maximum value. (b) Suppose you apply the brakes and do not turn the steering wheel. Find the minimum distance you must be from the wall to avoid a collision. (c) If you do not brake but instead maintain constant speed and turn the steering wheel, what is the minimum distance you must be from the wall to avoid a collision? (d) Of the two methods in parts (b) and (c), which is better for avoiding a collision? Or should you use both the brakes and the steering wheel, or neither? Explain. (c) Does the conclusion in part (d) depend on the numerical values given in this problem, or is it true in general? Explain.
Review. While learning to drive, you arc in a 1 200-kg car moving at 20.0 m/s across a large, vacant, level parking lot. Suddenly you realize you are heading straight toward the brick sidewall of a large supermarket and are in danger of running into it. The pavement can exert a maximum horizontal force of 7 000 N on the car. (a) Explain why you should expect the force to have a well-defined maximum value. (b) Suppose you apply the brakes and do not turn the steering wheel. Find the minimum distance you must be from the wall to avoid a collision. (c) If you do not brake but instead maintain constant speed and turn the steering wheel, what is the minimum distance you must be from the wall to avoid a collision? (d) Of the two methods in parts (b) and (c), which is better for avoiding a collision? Or should you use both the brakes and the steering wheel, or neither? Explain. (c) Does the conclusion in part (d) depend on the numerical values given in this problem, or is it true in general? Explain.
Solution Summary: The author explains that a well-defined horizontal force results in the slow acceleration of the car to avoid damages.
Review. While learning to drive, you arc in a 1 200-kg car moving at 20.0 m/s across a large, vacant, level parking lot. Suddenly you realize you are heading straight toward the brick sidewall of a large supermarket and are in danger of running into it. The pavement can exert a maximum horizontal force of 7 000 N on the car. (a) Explain why you should expect the force to have a well-defined maximum value. (b) Suppose you apply the brakes and do not turn the steering wheel. Find the minimum distance you must be from the wall to avoid a collision. (c) If you do not brake but instead maintain constant speed and turn the steering wheel, what is the minimum distance you must be from the wall to avoid a collision? (d) Of the two methods in parts (b) and (c), which is better for avoiding a collision? Or should you use both the brakes and the steering wheel, or neither? Explain. (c) Does the conclusion in part (d) depend on the numerical values given in this problem, or is it true in general? Explain.
3.63 • Leaping the River II. A physics professor did daredevil
stunts in his spare time. His last stunt was an attempt to jump across
a river on a motorcycle (Fig. P3.63). The takeoff ramp was inclined at
53.0°, the river was 40.0 m wide, and the far bank was 15.0 m lower
than the top of the ramp. The river itself was 100 m below the ramp.
Ignore air resistance. (a) What should his speed have been at the top of
the ramp to have just made it to the edge of the far bank? (b) If his speed
was only half the value found in part (a), where did he land?
Figure P3.63
53.0°
100 m
40.0 m→
15.0 m
Please solve and answer the question correctly please. Thank you!!
You throw a small rock straight up from the edge of a highway bridge that crosses a river. The rock passes you on its way down, 5.00 s after it was thrown. What is the speed of the rock just before it reaches the water 25.0 m below the point where the rock left your hand? Ignore air resistance.
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