Question

Three kids are riding on a snow sled traveling horizontally without friction at 19.8 m/s. The masses of Kid A, B, and C are 42.8 kg, 31.5 kg, and 25.9 kg, respectively.
What is the new velocity of the sled if Kid A jumps off vertically from the sled? (Kid A velocity = 0)

Answer 1

Answer:

34.6 m/s

Explanation:

Considering the law of conservation of linear momentum, the sum of initial and final momentum are equal. Momentum, p is given by mv where m is the mass of object and v is the velocity of the object. For this question

$M_iv_i=M_fv_f$

where subscripts I and f represent initial and final

The initial mass compose of all the three kids but the final mass excludes kid A

Substituting 19.8 m/s for initial velocity and the other masses as given then

the initial mass is 42.8+31.5+25.9=100.2 Kg

Final mass is 31.5+25.9=57.4 Kg

$100.2*19.8=57.4v_f\\v_f=\frac {100.2*19.8}{57.4}=34.56376307\ m/s\approx 34.6\ m/s$

Therefore, the new velocity is 34.6 m/s