Question

A 5.0 kg ball moving at 8.0 m/s strikes a stationary 85 kg man on the chest after which the ball bounces back at 2.0 m/s. If the man (who is wearing high quality roller blades) was originally at rest, what is his final velocity?

Answer 1

0.588 m/s forward

Step-by-step explanation:

From the law of conservation of momentum, the sum of initial and final momentum are equal hence for this case, it will be expressed as

`m_bu_b+m_mu_m=m_bv_b+m_mv_m`

Where m represnt mass, u and v represent initial and final velocities respectively, subscripts b and m represent ball and man respectively.

Since rhe man is initiallh at rest, then his initial velocity is zero.

Taking the forward direction as positive then backward direction when a ball bounces will be negative.

Substituting the mass of ball and man with 5 kg and 85 kg respectively, the initial velocity of ball with 8 m/s while final ball velocity as -2 m/s then we get

5*8+(85*0)=5*-2+(85v)

85v=50

V=0.5882352941176

Rounding off, the velocity of the man is approximately 0.588 m/s forward