This one seems to be a challenge.... Are you up for it? A ball of mass 200 g is

ID: 1439301 • Letter: T

Question

This one seems to be a challenge.... Are you up for it?

A ball of mass 200 g is released from rest at a height of 2.50 m above the floor and it rebounds straight up to a height of 0.800 m .

a) Determine the magnitude of the the ball's change in momentum due to its contact with the floor.

b) Determine the direction of the the ball's change in momentum due to its contact with the floor.

c) If the contact time with the floor was 0.0950 s , what was the average force the floor exerted on the ball?

d) What was the direction of this force?

Here’s what I do know…

a) 2.19 kgm/s

b) upward

c) the answer is NOT (according to Mastering Physics): 23.1 N, 14.7 N, 4.42 N, or 8.33 N

d) upward

here,

mass , m = 0.2 kg

initial height , h1 = 2.5 m

velocity before hitting ground , u = sqrt(2*g*h1)

u = - 7 m/s

height after rebounds , h2 = 0.8 m

velocity after hitting the ground , v = sqrt(2*g*h2)

v= sqrt(2*9.8*0.8)

v = 3.96 m/s

the magnitude of the the ball's change in momentum due to its contact with the floor , P = m * ( v - u)

P = 0.2 * ( 3.96 + 7 )

P = 2.19 kg.m/s

the direction of the the ball's change in momentum due to its contact with the floor is upwards

time of contact , t = 0.095 s,

average force , f = impulse / t

f = 2.19 /0.095

f = 23.07 N

the direction of force is upwards

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