A 2000-kg truck is sitting at rest (in neutral) when it is rear-ended by a 1000-

Question

A 2000-kg truck is sitting at rest (in neutral) when it is rear-ended by a 1000-kg car going 40 m/s .After the collision, the two vehicles stick together.

Part B

What is the kinetic energy of the two-vehicle system before the collision?

Express your answer to two significant digits and include the appropriate units.

Part C

What is the kinetic energy of the system after the collision?

Express your answer to two significant digits and include the appropriate units.

Kf=?

Part D

Based on the results of the previous parts, what can you conclude about which type of collision this is?

Based on the results of the previous parts, what can you conclude about which type of collision this is?

The collision is elastic

Part E

Calculate the coefficient of restitution for this collision.

e=?

The collision is elastic

Part E

Calculate the coefficient of restitution for this collision.

e=?

Explanation / Answer

here,

mass oftruck , mt = 2000 kg

mass of car , mc = 1000 kg

initial speed of car , uc = 40 m/s

part B)

the kinetic energy of the two-vehicle system before the collision , KE = 0.5 * mc *uc^2

KE = 0.5 * 1000 * 40^2

KE = 8.0 * 10^5 J

the kinetic energy of the two-vehicle system before the collision is 8*10^5 J

part C)

let the speed of vehicle after the collison be v

using conservation of momentum

mc*uc = (mc+mt) * v

1000 * 40 = (1000 + 2000) * v

v = 13.33 m/s

KEf = 0.5 * (mc + mt) * v^2

KEf = 0.5 * 3000 * 13.33^2

KEf = 2.7 *10^5

the kinetic energy of the system after the collision is 2.7 * 10^5 J

part D)

Final velociyt of both will be same

therefore , the final relative velocity is zero

the collison is inelastic and the coefficient of restitution for this collision , e = 0

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