Problem 111 Consider the ball of mass m 0.3 kg dropped from a height ho that is
ID: 1781325 • Letter: P
Question
Problem 111 Consider the ball of mass m 0.3 kg dropped from a height ho that is illustrated in Fig. 11.5. The speed of the ball at the instant of impact is V1 - 4.72 m/s. After hitting the floor, the ball bounces back and reaches a height h3. If the speed of the ball immediately after the impact is ½ 3.94 m/s and the duration of contact between the ball and the floor is t 001 s, determine: (a) The initial height, ho, of the ball (b) The height, h3, of the ball at point (3) (c) The momentum, pi, of the ball immediately before the impact (d) The momentum, p2, of the ball immediately after the impact (e) The change in momentum, Ap, of the ball during the impact (f) The magnitude of force, F, exerted by the floor on the ball during the impact Answers: (a) ho-1.14 m, (b) h3-0.79 m, (c) p,-1.42 kg m/s, (d) P2 1.18 kg m/s, (e) 2-26( kg m/s, (f) F = 260 NExplanation / Answer
a )
using equation
h = V12 / 2 g
h = 4.722 / 2 X 9.81
h = 1.14 m
b )
again h = V22 // 2 g
= 3.942 / 2 X 9.81
h = 0.79 m
c )
momentum P = m v
m V1 = 0.3 X 4.722
= 1.42 kg m/sec
d )
sameway P2 = 0.3 X V2
= 0.3 X 3.94
= 1.18 kgm/sec
e )
P = 1.42 - ( - 1.18 )
= 2.6 j kgm/sec
f )
F = 2 C / 0.01
= dp / dt
= 2.6 / 0.06
= 260 N