Question

- The speed of a car weighing 1500 kg increases from 36 km/h to 72 km/h uniformly. What will be the change in momentum of the car?

Answer 1

Given :

• Mass of the car(m) = 1500kg
• Initial velocity (u) = 36 km / hr = 36 x 5 / 18 = 10 m/s
• Final velocity(v) = 72 km / hr = 72 x 5 / 18 = 20 m/s

[ in order to convert km / hr into m/s multiply by 5 / 18 ]

To find :

• Change in momentum

Solution :

Momentum is given by the formula ,

$\dag \boxed{\pink{ P = mv }}$

here ,

• m = mass of the object
• v = speed of the object

So ,

Initial momentum of the car ,

$\leadsto P_i = m \times u$

$\leadsto P_i = 1500 \times 10$

$\leadsto P_i = 15000 \: kg m/s$

Final momentum of the car ,

$\leadsto P_f= m \times v$

$\leadsto P_i = 1500 \times 20$

$\leadsto P_i = 30,000 \: kg m/s$

Change in momentum ,

$\leadsto \Delta P = P_f -P_i$

$\leadsto \Delta P = 30,000 - 15,000$

$\leadsto \underline{\boxed{\red{\Delta P = 15,000 \: kg m/s }}}$

The change in momentum of the car is 15,000 kg m/s .