Question

pls answer as soon as possible! thanks.

A 3000 kg truck travelling at 50 km/hr strikes a stationary 1000 kg car, locking the two vehicles together.
A) What is the final velocity of the two vehicles?
B) How much of the initial kinetic energy is lost to the collision?

Answer 1

Solution)(A) m1 = 3000 kg

u1 = 50 km/hr

1 km/hr = (1000)/(3600) m/s = (5)/(18) m/s

50 km/hr = (50×5)/(18) m/s = 13.89 m/s

m2 = 1000 kg

u2 = 0 ( stationary )

V = ?

Applying Conservation of momentum

(m1)(u1) + (m2)(u2) = (m1 + m2)(V)

(3000)(13.89) + (1000)(0) = (3000 + 1000)(V)

V = (3000×13.89)/(3000 + 1000)

V = 10.42 m/s

(B) initial Kinetic Energy Lost , E = ?

E = KEi - KEf

E = [(1/2)(m1)(u1^2) + (1/2)(m2)(u2^2)] - (1/2)(m1+m2)(V^2)

E = (1/2)(3000)(13.89^2) + 0  - (1/2)(4000)(10.42^2)

E = 72,245.35 J

E = 72.245 KJ