Kevin has a mass of 87- kg and is skating with in-line skates. he sees his 22-kg younger brother up ahead standing on the sidewalk, with his back tuned. coming up, grabs his just before he brother and rolls off at a speed of 2.4 m/s. ignoring friction, find kevin speed just before he grabbed his brother.

3 m/s

Explanation:

M1 = 87 kg, u1 = ?

M2 = 22 kg, u = 0

After grabbing, let the velocity is V.

V = 2.4 m/s

By using the conservation of momentum

Momentum before grabbing = momentum after grabbing

M1 x u1 + M2 x u2 = (M1 + M2) x V

87 x u1 + 0 = (87 + 22) x 2.4

87 u1 = 261.6

u1 = 3 m/s

the total distance traveled by the car is

30km + 49km = 79 km .