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Roman55 [17]
3 years ago
13

When starting a foot race, a 70.0-kg sprinter exerts an average force of 650 n backward on the ground for 0.800 s. what is his f

inal speed?
Physics
1 answer:
VladimirAG [237]3 years ago
6 0
Given:
m = 70 kg, mass
F = 650 N, force
t = 0.8 s, time

Calculate the acceleration.
a = F/m = (650 N)/(70 kg)
   = 9.2857 m/s²

Because the initial velocity is zero, the final velocity (after time 0.8 s) is 
v = a*t = (9.2857 m/s²)*(0.8 s)
   = 7.43 m/s

Answer: 7.43 m/s  (nearest hundredth)
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A race car starting from rest accelerates uniformly at a rate of 4.90 meters per squared. What is the cars speed after it has tr
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Ok, we need to find a relation for the speed as it relates to the acceleration.  This is given by the integral of acceleration:

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But we see there is an issue now... We know the velocity as a function of time, but we don't know how long the car has been accelerating!  We need to calculate this time by now finding the position function as a function of time.  This way we can solve for the time, t, that it takes to go 200m accelerating this way and then substitute that time into our velocity equation and get the velocity. 
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s= \int\limits^{}_{} {at} \, dt = \frac{1}{2}at^2

Where the initial velocity and initial position are both zero.

Now we set this position function equal to 200m and find the time, t, it took to get there

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3 years ago
Hook's law describes an ideal spring. Many real springs are better described by the restoring force (FSp)s=−kΔs−q(Δs)^3, where q
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Answer

given,

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