A girl of mass 40 kg jumps with a horizontal velocity of 5m/s onto a stationary cart with frictionless wheels.The mass of the cart is 3 kg.What is her velocity as the cart starts moving?Assume that there is no external unbalnaced force working in the horizontal direction.

 

Asked by rufinusrath | 28th Oct, 2020, 12:44: PM

Expert Answer:

we need to apply momentum conservation to get the final speed of girl who jumped on the cart
 
Initial momentum = mass of girl × intial horizontal speed = 40 × 5 = 200 kg m/s
 
Momentum of girl and cart after jumping = ( 40 +3 ) × v  kg m/s
 
where v is the final speed of cart+Girl after jumping.
 
By conservation of momentum,  ( 40 +3 ) × v = 200  or  v = ( 200 / 43 ) m/s = 4.65 m/s

Answered by Thiyagarajan K | 28th Oct, 2020, 04:33: PM