Problema Solution
A 50kg ballet dancer makes a leap to the left at a speed of 5m/s on to the arms of her partner at rest.The male dancer exerts a steady horizontal force of 350N while catching his partner to a stop. What is the time to reduce her momentum to zero?
Answer provided by our tutors
Let M = initial momentum of the dancer,
m = mass of the dancer = 50
kg
v = initial speed of the dancer = 5 m/s
=> M = mv = 50 x 5 =
250 kgm/s
Final momentum of the dancer = 0
By
definition,
Force = rate of change in momentum (Change in momentum per
unit time) = 350 N
Let t = time taken to reduce the momentum to
0
=> 350 N = (250 kgm/s - 0) / t
=> t = 250 / 350 s
= 0.71 s