Unit 2 Section 3 Practice Scrimmage

What is the definition of momentum in physics?

• The rate of change of velocity

• The product of mass and velocity

• The force applied over time

• The energy stored in an object

Answer explanation

Momentum in physics is defined as the product of mass and velocity. This means that an object's momentum depends on how much mass it has and how fast it is moving, making 'the product of mass and velocity' the correct choice.

Tags

NGSS.HS-PS2-2

Which of the following is the correct formula for impulse?

Identify the type of collision where kinetic energy is not conserved.

• Elastic collision

• Inelastic collision

• Perfectly elastic collision

• Superelastic collision

Answer explanation

In an inelastic collision, kinetic energy is not conserved, although momentum is. This contrasts with elastic collisions, where both momentum and kinetic energy are conserved.

In a closed system, what is conserved during a collision?

• Kinetic energy

• Momentum

• Force

• Impulse

Answer explanation

In a closed system, momentum is conserved during a collision, meaning the total momentum before the collision equals the total momentum after. Kinetic energy may not be conserved in inelastic collisions.

Tags

NGSS.HS-PS2-2

Calculate the impulse experienced by an object when a force of 10 N is applied for 5 seconds.

• 50 Ns

• 5 Ns

• 15 Ns

• 2 Ns

Answer explanation

Impulse is calculated as the product of force and time. Here, impulse = force × time = 10 N × 5 s = 50 Ns. Therefore, the correct answer is 50 Ns.

Tags

NGSS.HS-PS2-2

A car of mass 1000 kg is moving at a velocity of 20 m/s. What is its momentum?

• 2000 kg·m/s

• 20000 kg·m/s

• 500 kg·m/s

• 5000 kg·m/s

Answer explanation

Momentum is calculated using the formula: momentum = mass × velocity. Here, mass = 1000 kg and velocity = 20 m/s. Thus, momentum = 1000 kg × 20 m/s = 20000 kg·m/s, which is the correct answer.

Tags

NGSS.HS-PS2-2

Which of the following scenarios is an example of an inelastic collision?

• Two billiard balls colliding and bouncing off each other

• A car crash where the cars stick together

• A rubber ball bouncing off the ground

• A tennis ball hitting a racket and bouncing back

Answer explanation

An inelastic collision occurs when objects collide and stick together, conserving momentum but not kinetic energy. The car crash where the cars stick together is a clear example of this, unlike the other scenarios.

Tags

NGSS.HS-PS2-3

A 2 kg object moving at 3 m/s collides with a 1 kg object at rest. If they stick together after the collision, what is their final velocity?

• 1 m/s

• 2 m/s

• 3 m/s

• 4 m/s

Answer explanation

Using conservation of momentum: (2 kg * 3 m/s) + (1 kg * 0 m/s) = (2 kg + 1 kg) * v. This simplifies to 6 kg*m/s = 3 kg * v, giving v = 2 m/s. Thus, the final velocity is 2 m/s.

Tags

NGSS.HS-PS2-2

Explain why momentum is conserved in a closed system.

• Because external forces are balanced

• Because energy is always conserved

• Because the system is isolated from external influences

• Because mass is constant

Answer explanation

Momentum is conserved in a closed system because the system is isolated from external influences. This means no external forces act on the system, allowing the total momentum to remain constant.

Tags

NGSS.HS-PS2-2

A force of 15 N is applied to a 3 kg object for 4 seconds. What is the change in momentum of the object?

• 45 kg·m/s

• 60 kg·m/s

• 75 kg·m/s

• 90 kg·m/s

Answer explanation

The change in momentum is calculated using the formula: momentum change = force × time. Here, 15 N × 4 s = 60 kg·m/s. Thus, the correct answer is 60 kg·m/s.

Tags

NGSS.HS-PS2-1