Physics word problem.PLEASE HELP !!!!!!?

Question

A 0.20 kg baseball moving at +20.60 m/s is slowed to a stop by a catcher who exerts a constant force of -351 N.
How long does it take this force to stop the ball?
How far does the ball travel before stopping?

Answer 1

The energy of the ball is
.5*0.2*20.6^2

The acceleration of the ball is
=-351/0.2
-1755 m/s^2

the motion of the ball is
vx(t)=20.6-1755*t
when vx(t)=0, the ball stops
t=0.0117 seconds

the distance is
x(t)=20.6*t-.5*1755*t^2
0.12 m

check using energy
42.436=351*d
d=0.12 m checks

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