Q6: The speed of a car weighing 1500 kgs increases from 36 km/hr to 72 km/hr
uniformly. What will be the change in the momentum of car:
a) 15000 kg km/hr
b) 15000 kg m/s
c) 54000 kg m/s
d) 54000 g m/s
Answers
Correct Question -
The speed of a car weighing 1500 kg increases from 36 km/hr to 72 km/hr uniformly.
What will be the change in the momentum of car ?
a) 15000 kg km/hr
b) 15000 kg m/s
c) 54000 kg m/s
d) 54000 g m/s
the above Question , the following information is given -
The weight of the car is 1500 kg .
The initial Velocity of the car is 36 kmph
The final Velocity of the car is 72 kmph .
So ,
Change in velocity of car -
∆V
=> 72 - 46
=> 36 kmph
Now
The mass of the car is 1500 kg
Change In Momentum
=> mv² - mv¹
=> m ( v² - v ¹ )
=> m ∆ v
=> 1500 × 36 kg kmph
=> 5400 kg kmph
Now, none of the options matches let change the units.
So ,
Initial Velocity
=> 36 kmph
=> 36 × ( 5 / 18 ) m /s.
=> 10 m / s.
Final velocity
=> 72 kmph
=> 72 × ( 5 / 18 ) m / s
=> 20 m /s.
∆ V
=> 10 m / s
Change in Momentum -
=> m ∆ v
=> 1500 × 10 kg m / s
=> 15000 kg m / s.
Hence , option B is the correct answer.
________
☞ Your answer is option b
✭ Weight of the car = 1500 kg
✭ Speed changes from 36 km/h to 72 km/h
☆ Change in the momentum of the car?
Initial velocity = 36 km/h = 36 × = 10m/s
Final velocity = 72 km/h = 72 × = 20m/s
So the change in momentum is given by,
Substituting the given values,
➝ 1500 × 20 - 1500 × 10
➝ 30000 - 15000
➝