Question

A 200 kg motorcycle speeds at 90 mph (40 m/s) off of a highway overpass and lands on top of a 18,000 kg semi truck, which is traveling in the same direction at 65 mph (30 m/s). Assume both vehicles stick together are coasting without friction after the collision. What will be the final speed of the semi truck after the collision

Answer 1

The final speed of the semi truck is 30.11 m/s.

Step-by-step explanation:

Given;

mass of the motorcycle, m₁ = 200 kg

initial speed of the motorcycle, u₁ = 40 m/s

mass of the semi truck , m₂ = 18,000 kg

initial speed of the semi truck, u₂ = 30 m/s (same direction as u₁)

If the two vehicles stick together after collision, the final speed of the motorcycle will be equal to final speed of the semi truck = v

Apply the principle of conservation of linear momentum;

m₁u₁ + m₂u₂ = v(m₁ + m₂)

(200 x 40) + (18,000 x 30) = v(200 + 18,000)

8000 + 540,000 = v(18,200)

548,000 = v(18,200)

`v = (548,000)/(18,200) \\\\v = 30.11 \ m/s`

Therefore, the final speed of the semi truck is 30.11 m/s.