1 In an ice show a 70.0 kg skater leaps into the air and is caught by an initial

Question

1 In an ice show a 70.0 kg skater leaps into the air and is caught by an initially stationary 60.0 kg skater.

(a) What is their final velocity assuming negligible friction and that the leaper's original horizontal velocity was 4.00 m/s?
m/s
(b) How much kinetic energy is lost?
J

2 A man holding a rock sits on a sled that is sliding across a frozen lake (negligible friction) with a speed of  0.450 m/s. The total mass of the sled, man, and rock is 97.5 kg. The mass of the rock is 0.320 kg and the man can throw it with a speed of 17.5 m/s. Both speeds are relative to the ground. Determine the speed of the sled if the man throws the rock forward (i.e. in the direction the sled is moving).
m/s

Determine the speed of the sled if the man throws the rock directly backward.
m/s

Explanation / Answer

Here ,

m1 = 70 Kg

m2 = 60 Kg

a) let the final velocity is v

Using conservation of momentum

v * (70 + 60) = 70 * 4

v = 2.15 m/s

the final velocity is 2.15 m/s

b) Kinetic Energy lost = initial energy - final energy

Kinetic Energy lost = 0.50 * 70 * 4^2 - 0.50 * (60 + 70) * 2.15^2

Kinetic Energy lost = 259 J

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