A car with a mass of 2000 kg travels to the right at a speed of 80 m/s. A truck travels to the left at a speed of 20 m/s and has a mass of 7000 kg. Which one of the two has the greatest momentum? Cannot tell without the impulse

The truck

Both have the same momentum

The car

The car has the greatest momentum, 160000 [kg*m/s]

Explanation:

In order to solve this problem we must remember that linear momentum is defined as the product of mass by Velocity. In this way we have the following equation

P = m*v

where:

P = lineal momemtum [kg*m/s]

m = mass [kg]

v = velocity [m/s]

Therefore we must calculate the momentum for both the truck and the car.

For the car

Pc = 2000*80

Pc = 160000 [kg*m/s]

For the Truck

Pt = 7000*20

Pt = 140000 [m/s]

The car has the greatest momentum

when two balls of the different masses are dropped from equal height, they reach the ground at the same time .this is because they experience the same acceleration.

the acceleration is independent of mass.

thus when they are dropped they will always maintain the same velocity and travel the same distance (neglect air resistance of course) at the same time.

force is based upon mass and acceleration.the statement is not always true.

it can be explained from newton's second law of motion.

as per newton's second law of motion the rate of change of momentum is directly proportional to the applied force and takes place along the direction of force.

mathematically it can be written as -

                                              ⇒      

here   k is the proportionality constant whose value is 1.

                                                            [a is the acceleration=dv/dt]

hence we see that force not only depends on mass and acceleration but also on velocity and rate of change of mass. force f will depend on mass and acceleration only when mass is constant.

hence the statement that force is based upon mass and acceleration is false.