Review. A force platform is a tool used to analyze the performance of athletes by measuring the vertical force the athlete exerts on the ground as a function of time. Starting from rest, a 65.0-kg athlete jumps down onto the platform from a height of 0.600 m. While she is in contact with the platform during the time interval 0< t < 0.800 s, the force she exerts on it is described by the function F = 9 200t – 11 500 t 2 where F is in newtons and t is in seconds. (a) What impulse did the athlete receive from the platform? (b) With what speed did she reach the platform? (c) With what speed did she leave it? (d) To what height did she jump upon leaving the platform?
Review. A force platform is a tool used to analyze the performance of athletes by measuring the vertical force the athlete exerts on the ground as a function of time. Starting from rest, a 65.0-kg athlete jumps down onto the platform from a height of 0.600 m. While she is in contact with the platform during the time interval 0< t < 0.800 s, the force she exerts on it is described by the function F = 9 200t – 11 500 t 2 where F is in newtons and t is in seconds. (a) What impulse did the athlete receive from the platform? (b) With what speed did she reach the platform? (c) With what speed did she leave it? (d) To what height did she jump upon leaving the platform?
Solution Summary: The author explains that the impulse received from the platform to the athlete is 981.33Ncdot s.
Review. A force platform is a tool used to analyze the performance of athletes by measuring the vertical force the athlete exerts on the ground as a function of time. Starting from rest, a 65.0-kg athlete jumps down onto the platform from a height of 0.600 m. While she is in contact with the platform during the time interval 0<t< 0.800 s, the force she exerts on it is described by the function
F = 9 200t – 11 500 t2
where F is in newtons and t is in seconds. (a) What impulse did the athlete receive from the platform? (b) With what speed did she reach the platform? (c) With what speed did she leave it? (d) To what height did she jump upon leaving the platform?
A student (m = 58 kg) falls freely from rest and strikes the ground. During the collision with the ground, he comes to rest in a time of
0.04 s. The average force exerted on him by the ground is +18000 N, where the upward direction is taken to be the positive direction.
From what height did the student fall? Assume that the only force acting on him during the collision is that due to the ground.
H=
A worker pushes a 35.0-kg package on a horizontal roller-belt conveyor until it reaches a certain speed. The package then coasts on the horizontal conveyor, all the while slowing down, until it
comes to a complete stop after moving 1.20 m. While the package is coasting on the conveyor, the opposing friction force averages 6.00 N. Use the WET to find the speed of the package
after the worker pushes it and just as it begins to coast.
0.625 m/s
0.759 m/s
0.600 m/s
0.510 m/s
0.802 m/s
0.641 m/s
Current Attempt in Progress
The figure shows a cold package of hot dogs sliding rightward across a frictionless floor through a distance d = 22.0 cm while three
forces act on the package. Two of them are horizontal and have the magnitudes F₁ = 8.0 N and F₂ = 2.0 N; the third is angled down by
= 60.0° and has the magnitude F3 = 7.0 N. (a) For the 22.0 cm displacement, what is the net work done on the package by the three
applied forces, the gravitational force on the package, and the normal force on the package? (b) If the package has a mass of 4.0 kg and
an initial kinetic energy of 0, what is its speed (in m/s) at the end of the displacement?
(a) Number i
(b) Number
Units
Units
Hot Dogs
Ve
F
F
d
Chapter 9 Solutions
Physics for Scientists and Engineers, Technology Update (No access codes included)
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