Question

Two ice skaters, with masses of 71 kg and49 kg , stand facing each other on a 11-m-widefrozen river. The skaters push off against each other, glide backward straight toward the river's edges, and reach the edges at exactly the same time.

How far did the 71 kg skater glide?

Express your answer to two significant figures and include the appropriate units

Answer 1

Here ,

mass , m1 = 71 Kg

mass , m2 = 40 Kg

let the 71 kg skater is x m from the edge

v1 is the speed of 71 kg

v2 is the speed of 40 kg

distance of 40 Kg = 11 - x

Now , as there is no external force acting on system of skaters

change in momentum = 0

m1 * v1 - m2 * v2 = 0

71 * v1 = 40 * v2 ---(1)

Now ,as the time taken to reach is same for both

d1/v1 = d2/v2

x/(v1) = (11 - x)/v2

from 1

x/(40 * v2/71) = (11 - x)/v2

x/(40/71) = (11 - x)

x = 3.96 m

the 71 kg glider is 3.96 m from the edge