Question

A 90.5kg man standing on a surface of negligible friction kicks forward a 45gm stone lying at his feet so that it acquires a speed of 3.05m/s. what velocity does the main acquire as a result?​

Answer 1

Answer:

0.0015

Explanation:

Given parameters:

Mass of man = 90.5kg

Mass of stone = 45g

Speed of stone  = 3.05m/s

Unknown:

Velocity of man  = ?

Solution:

What relates the man to the stone is the momentum. The momentum lost by man in kicking the stone is gained by the moving stone. This way momentum is conserved.

Momentum  = mass x velocity

         Momentum lost by man = momentum gained by stone

              M₁V₁  = M₂V₂

1 denotes man

2 denotes stone

            since V₁ is unknown, we make it the subject in the expression.

   convert mass to kg;

           45g  =  0.045kg

       V₁   =   $\frac{M_{2} V_{2} }{_{M1} }$  = $\frac{0.045 x 3.05}{90.5}$  

    V₁   = 0.0015m/s