Question

An SUV with a mass of 1.80 103 kg is travelling eastbound with a speed of 15.0 m s while a compact car with a mass of 9.00 102 kg is travelling westbound at 15.0 m s The vehicles collide head on and stick together What is the speed of the wreck immediately after the collision and which way does it move

Answer 1

5 m/s

Step-by-step explanation:

mass of SUV (M1) = 1.80 x 10^{3} kg = 1800 kg

velocity of SUV (V1) = 15 m/s

mass of car (M2) = 9 x 10^{2} kg = 900 kg

velocity of car (V2) = 15 m/s

let the direction of motion eastward ( to the right ) be positive while the direction of motion westward (to the left ) be negative, therefore

velocity of SUV (V1) = 15 m/s

velocity of car (V2) = -15 m/s

now applying the conservation of momentum

(M1)(V1) + (M2)(V2) = (M1 + M2) x Vf

where Vf is the final velocity after collision

(1800 x 15) + (900 x (-15)) = (1800 + 900) x Vf

27000 - 13500 = 2700Vf

13500 = 2700 Vf

Vf = 5 m/s