Question

- A 1250 kg car is stopped at a traffic light. A 3550 kg truck moving at 8.33m/s hits the car from behind. If bumpers lock, how fast will the two vehicles move?​
Pls give good explanation...

Answer 1

Mass of the car ,m1= 1250 kg

Mass of the truck, m2=3550 kg

Initial velocity of car, u1= 0 m/s [ Car is stopped]

Initial velocity of the truck= 8.33 m/s

Final Velocities i.e. v1 = v2 [Since the bumpers get locked]

According to law of conservation of momentum,

m1u1+m2u2=m1v1+ m2v2

=> m1u1+m2u2= (m1+m2)v [ Taking v

common,

since v1=v2]

=>(1250kg×0m/s)+(3550kg×8.33m/s)

= (1250kg+3550kg)v

=> 0kgm/s+29571.5kgm/s=4800 kg×v

=> 29571.5kgm/s=4800 kg×v

Now

v= 29571.5kgm/s÷4800 kg

v= 6.16 m/s

So, the vehicles will move with the velocity of 6.16 m/s

Hope it's correct!