Question

A car has a mass of 900 kg and a truck has a mass of 1800 kg. In which of the following situations would they have the same momentum?
The car travels at twice the velocity of the truck.

The car and truck travel at the same velocity.

The truck has a negative acceleration.

The car has a positive acceleration.

Answer 1

a) since force = mass * acceleration  

f= 900 * 0 (because constant speed = 0 acceleration)  

similarly b) f = 0

Answer 2

Answer:

The car travels at twice the velocity of the truck.

Explanation:

As we know that momentum is defined as the product of mass and velocity

so here we know

mass of the car = 900 kg

mass of the truck = 1800 kg

now let say that the speed of car = $v_1$

speed of truck = $v_2$

so if the momentum of car and truck is same

$900 v_1 = 1800 v_2$

$v_1 = 2 v_2$

so we can say that car will move with double the speed of truck