CP Jumping to the Ground. A 75.0-kg man steps off a platform 3.10 m above the ground. He keeps his legs straight as he falls, but his knees begin to bend at the moment his feet touch the ground; treated as a particle, he moves an additional 0.60 m before coming to rest. (a) What is his speed at the instant his feet touch the ground? (b) If we treat the man as a particle, what is his acceleration (magnitude and direction) as he slows down, if the acceleration is assumed to be constant? (c) Draw his free-body diagram. In terms of the forces on the diagram, what is the net force on him? Use Newton’s laws and the results of part (b) to calculate the average force his feet exert on the ground while he slows down. Express this force both in newtons and as a multiple of his weight.
CP Jumping to the Ground. A 75.0-kg man steps off a platform 3.10 m above the ground. He keeps his legs straight as he falls, but his knees begin to bend at the moment his feet touch the ground; treated as a particle, he moves an additional 0.60 m before coming to rest. (a) What is his speed at the instant his feet touch the ground? (b) If we treat the man as a particle, what is his acceleration (magnitude and direction) as he slows down, if the acceleration is assumed to be constant? (c) Draw his free-body diagram. In terms of the forces on the diagram, what is the net force on him? Use Newton’s laws and the results of part (b) to calculate the average force his feet exert on the ground while he slows down. Express this force both in newtons and as a multiple of his weight.
CP Jumping to the Ground. A 75.0-kg man steps off a platform 3.10 m above the ground. He keeps his legs straight as he falls, but his knees begin to bend at the moment his feet touch the ground; treated as a particle, he moves an additional 0.60 m before coming to rest. (a) What is his speed at the instant his feet touch the ground? (b) If we treat the man as a particle, what is his acceleration (magnitude and direction) as he slows down, if the acceleration is assumed to be constant? (c) Draw his free-body diagram. In terms of the forces on the diagram, what is the net force on him? Use Newton’s laws and the results of part (b) to calculate the average force his feet exert on the ground while he slows down. Express this force both in newtons and as a multiple of his weight.
Race car driver is cruising down the street at a constant speed of 28.9 m/s (~65 mph; he has a “lead” foot) when the traffic light in front of him turns red. a) If the driver’s reaction time is 160 ms, how far does he and his car travel down the road from the instant he sees the light change to the instant he begins to slow down? b) If the driver’s combined reaction and movement time is 750 ms, how far do he and his car travel down the road from the instant he sees the light change to the instant he slams on her brakes and car begins to slow down? Please answer parts a-B. Show all work. For each question draw a diagram to show the vector/s. Show all the step and provide units in the answers. Provide answer to 2 decimal places. DONT FORGET TO DRAW VECTORS! ONLY USE BASIC FORMULAS TAUGHT IN PHYSICS. distance = speed * time.
Race car driver is cruising down the street at a constant speed of 28.9 m/s (~65 mph; he has a “lead” foot) when the traffic light in front of him turns red. a) If the driver’s reaction time is 160 ms, how far does he and his car travel down the road from the instant he sees the light change to the instant he begins to slow down? b) If the driver’s combined reaction and movement time is 750 ms, how far do he and his car travel down the road from the instant he sees the light change to the instant he slams on her brakes and car begins to slow down? c) If the driver’s average rate of acceleration is -9.5 m/s2 as he slows down, how long does it take him to come to a stop (use information about his speed of 28.9 m/s but do NOT use his reaction and movement time in this computation)? Please answer parts a-c. Show all work. For each question draw a diagram to show the vector/s. Show all the step and provide units in the answers. Provide answer to 2 decimal places unless stated otherwise.…
How is it that part a is connected to part b? I can't seem to solve either part and don't see the connection between the two.
Chapter 4 Solutions
University Physics with Modern Physics, Volume 1 (Chs. 1-20) and Mastering Physics with Pearson eText & ValuePack Access Card (14th Edition)
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