1) usain bolt just crossed the finish line of the 100 meter race at a speed of 1

Question

1) usain bolt just crossed the finish line of the 100 meter race at a speed of 11.0 m/s. immediately, he begins to slow down at a rate of 2.4 m/s^2. After another two seconds, how far is he behind the starting blocks?

2) You throw a ball an angle of 40 degrees above the horizontal. How fast must you throw the ball, such that its speed at the top of the trajectory is 4.8 m/s?

3) You throw a ball at an angle of 40 degrees above the horizontal. How fast must you throw the ball, such that at the top of its trajectory the vertical component of its velocity vector is zero?

4) You maintain a speed of 47 mph while driving your car through a narrow turn. is this statement true? Your velocity changes, thus the car is accelerating. Detailed answers Please! and thank you!

Explanation / Answer

1) x = v0 t + 1/2 a t^2 = 11*2 - 0.5*2.4*2^2= 17.2 m

2) at top vy = 0

so v0x = 4.8 m/s

cos theta = v0x/v

v = 4.8/cos(40 degrees)= 6.27 m/s

3) at top vertical is always zero so any speed.. trick questions

4)

Yes since the direction of your velocity is chaning

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