You are standing on a sheet of ice that covers the football stadium parking lot in Buffalo; there is negligible friction between your feet and the ice. A friend throws you a 0.405 kg ball that is traveling horizontally at 11.5 m/s . Your mass is 71.5 kg .

Question

If you catch the ball, with what speed do you and the ball move afterwards? If the ball hits you and bounces off your chest, so that afterwards it is moving horizontally at 7.80 m/s in the opposite direction, what is your speed after the collision?

Answer 1

Case A:

Taking your mass as M
Mass of the ball as m
Initial ball speed as u
Final combined speed as v:

Using conservation of momentum -

Initial momentum = Final momentum
mu = (M + m)v
0.405*11.5 = (71.5+0.405)V
V = 4.6575/71.905
= 0.0647 m/sec
= 6.47 cm/s

Answer 2

M1 = 0.405 kg, M2 = 71.5 kg.

M1*V1 + M2*V2 = M1*V + M2*V.
0.405*11.5 + 71.5*0 = 0.405V + 71.5V.
4.66 + 0 = 71.905V,
V = 0.0467 m/s. = 4.67 cm/s.

v

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