Brian is attempting to high jump over a crossbar set at 2.44 m (8 ft). At the in

Question

Brian is attempting to high jump over a crossbar set at 2.44 m (8 ft). At the instant of takeoff (when he is no longer in contact with the ground) his vertical velocity is 4.0 m/s, and his center of gravity is 1.25 m high.

a. What is Brian%u2019s vertical acceleration at the instant of takeoff?

answer:9.81 m/s2 downward

I need workout steps please.

b. How much time elapses after takeoff until Brian reaches his peak height?

answer:0.41 s

I need workout steps please.

c. What peak height does Brian%u2019s center of gravity achieve?

answer:2.07 m

I need workout steps please.

Explanation / Answer

A.While airborne, vertical acceleration stays at a constant -9.8m/s2

B.Flight time = 2v/(-g)=2*4/-(-9.8)= 0.816326 s. Since the high point would be half of

the flight time, peak height will be attained at 0.408 s.

C.Maximum height = v^2/-(2g)=4^2/-(-2*9.8)=16/19.6=0.816236

Since he began at 1.25 m, we must add 1.25 m to 0.816236 m = 2.066 m

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