Impulse and Momentum I

The momentum of an object depends upon the object's ___________&_____________.  

• size and shape

• mass and speed

• mass and veloctiy

• mass and energy

Answer explanation

The momentum of an object is defined as the product of its mass and velocity. Therefore, the correct answer is 'mass and velocity', as both factors directly influence the momentum.

The equation to calculate momentum is

• p=mv

• p=1/2mv²

• p=mgh

• p=mg

Answer explanation

The correct equation for momentum is p=mv, where p is momentum, m is mass, and v is velocity. The other options represent different physical concepts: kinetic energy, potential energy, and weight.

Which has more momentum: a car stopped at a red light or a bike moving at 15 mph?

• car

• bike

• they are equal

• cannot determine using the info provided

Answer explanation

Momentum is the product of mass and velocity. The car at a red light has zero velocity, thus zero momentum. The bike, moving at 15 mph, has momentum greater than zero. Therefore, the bike has more momentum.

In any collision (crash) the ______ is ALWAYS constant

• Total Momentum

• total speed

• total Velocity

• Energy

Answer explanation

In any collision, the total momentum is always conserved, meaning it remains constant before and after the crash. This principle is fundamental in physics, unlike total speed, total velocity, or energy, which can change.

A 0.250 kg cart moving at 0.400 m/s has how much momentum?

• 0.1 kg-m/s

• 1 kg-m/s

• 10 kg-m/s

• 100 kg-m/s

Answer explanation

Momentum is calculated using the formula p = mv. Here, p = 0.250 kg * 0.400 m/s = 0.1 kg-m/s. Therefore, the correct answer is 0.1 kg-m/s.

The impulse is ______ the change in momentum

• Greater than

• Equal to

• less than

• always double

Answer explanation

The impulse is defined as the product of force and the time duration over which it acts. According to the impulse-momentum theorem, impulse is equal to the change in momentum, making 'Equal to' the correct choice.

A boy kicks a football with a force of 20 N, the time the force acts for is 0.3 s.
Calculate the impulse on the ball.

• 1 N*s

• 6 N*s

• 33.3 N*s 

• None of these

Answer explanation

Impulse is calculated as force multiplied by time. Here, impulse = 20 N * 0.3 s = 6 N*s. Therefore, the correct answer is 6 N*s.

When the speed of an object is doubled, its momentum

• remains unchanged in accord with the conservation of momentum.

• doubles

• quadruples

• decreases

Answer explanation

When the speed of an object is doubled, its momentum, which is the product of mass and velocity, also doubles. Therefore, the correct answer is that the momentum doubles.

If the change of momentum of an object is 50kg m/s, we can say the impulse is equal to:

• 0 N*s

• 25 N*s

• 50 N*s

• 100 N*s

Answer explanation

Impulse is defined as the change in momentum. Since the change of momentum is 50 kg m/s, the impulse is also 50 N*s. Therefore, the correct answer is 50 N*s.

An object having a p_i of 30kg m/s has ended with a p_f of 40 kg m/s. What impulse caused this?

• 2 N*s

• 10 N*s

• 70 N*s

• 5 N*s

Answer explanation

Impulse is the change in momentum. Here, \( \Delta p = p_f - p_i = 40 \text{ kg m/s} - 30 \text{ kg m/s} = 10 \text{ kg m/s} \). Thus, the impulse that caused this change is 10 N*s.