Question

3. A loaded lorry of mass 12000 kg moves with a velocity of 12 m/s.
Its velocity becomes 10 m/s after 5 s.
a) What is the initial momentum and what is the final momentum ?
b) What is the change in momentum?
c) What is the rate of change of momentum?​

Answer 1

Solution :-

As per the given data ,

• Mass of the loaded (M) = 12000 kg

• Initial velocity (u) = 12 m/s

• Final velocity (v ) = 10 m /s

• Time taken ( t) = 5 s

(a)

Initial momentum ( Pi)

➝ Pi  = m u

➝ Pi  = 12000 x 12

➝ Pi  = 1,44,000 kg m/s

Final  momentum ( Pf)

➝ Pf  = m u

➝ Pf  = 12000 x 10

➝ Pf  = 1,20,000 kg m/s

(b) Change in momentum (ΔP)

ΔP = Pf - Pi

ΔP = 1,20,000 - 1,44,000

ΔP = - 24,000 kg m/s

(c) Rate of change of momentum ( F )

F = ΔP / t

F = 24,000/ 5\

F = - 4800 N

Answer :-

• Initial momentum of the lorry = 1,44,000 kg m/s

• Final momentum of the lorry = 1,20,000 kg m/s

• Change in momentum = - 24,000 kg m/s

• The rate of change of momentum = - 4800 N