Two ice skaters, with masses of 40.0 kg and 65.0 kg , are at the center of a 50.0 m -diameter circular rink. The skaters push off against each other and glide to opposite edges of the rink. Part A If the heavier skater reaches the edge in 10.0 s , how long does the lighter skater take to reach the edge

6.15 s

Explanation:

From the question,

Applying the law of conservation of momentum

Momentum of the Heavier skater = Momentum of the lighter skater.

Mv = mV Equation 1

Where M = mass of the heavier skater, m = mass of the lighter skater, v = Velocity of heavier skater, V = velocity of the lighter skater.

But,

v = r/t Equation 2

V = r/t' Equation 3

Where r = radius of the circular rink, t = time taken for the heavier skater to reach the edge, t' = time taken for the lighter skater to reach the edge.

Substitute equation 2 and equation 3 into equation 1

M(r/t) = m(r/t') Equation 4

Given: M = 65 kg, m = 40 kg, r = 50/2 = 25 m, t = 10 s.

Substitute into equation 4 and solve for t'

65(25/10) = 40(25/t')

162.5 = 1000/t'

t' = 1000/162.5

t' = 6.15 seconds

note: the given question is incomplete.

complete question is given below.

which is an example of kinetic energy?

a. the energy stored in ethanol  

b. a hockey puck sliding across the ice  

c. a compressed spring  

d. a ball sitting at the top of a ramp

solution: the kinetic energy is the energy posses by the virtue of the motion of the object.

in the given options, a, c and d are the example of potential energy because it is the energy posses by the virtue of the rest of the object. but option b has the kinetic energy as the object is in motion.

hence, a hockey puck sliding across the ice   is the apex example of kinetic energy.

so, the option (b) a hockey puck sliding across the ice   is the correct option.