6B Unit 3 Lesson 7-12

Momentum is the mass times the __________of the object

• weight

• acceleration

• velocity

• • 
    

    net force

Answer explanation

Momentum is defined as the product of an object's mass and its velocity. Therefore, the correct answer is 'velocity', as it directly relates to how momentum is calculated.

Tags

NGSS.MS-PS3-1

A student drew a force diagram for walking their dog. An arrow pointing from left to right shows the student pulling on the leash with a force of 20 N. An arrow from right to left shows the dog pulling on the leash in the opposite direction with a force of 10 N. What is the net force and direction?

• 10 N to the right

• 0 N. The dog does not move

• 5 N to the right

• • 
    

    10 N to the left

Answer explanation

The net force is calculated by subtracting the dog's pull (10 N) from the student's pull (20 N). This results in a net force of 10 N to the right. However, since the dog is pulling back, the forces balance out, resulting in 0 N. The dog does not move.

Tags

NGSS.MS-PS2-1

NGSS.MS-PS2-2

A student wants to find the net force on an object. They have the mass and the acceleration of the object. What must the student do?

• • 
    

    Add mass plus acceleration

• Divide mass by acceleration

• • 
    

    Subtract acceleration from mass

• Multiply mass times acceleration

Answer explanation

To find the net force on an object, the student should use Newton's second law of motion, which states that force equals mass times acceleration (F = ma). Therefore, they must multiply mass by acceleration.

Tags

NGSS.MS-PS2-1

NGSS.MS-PS2-2

A student drew a net force diagram for a stone. What is the amount and direction of the net force acting on the stone?

• • 
    

    6 N downward

• 4 N upward

• 10 N downward

• • 
    

    0 N. The stone does not move.

Answer explanation

The net force on the stone is 6 N downward, indicating that the downward forces exceed any upward forces. This choice reflects the correct balance of forces acting on the stone.

Tags

NGSS.MS-PS2-2

What is accomplished by this simple pulley? 

• • 
    

    It changes the total work done to lift the object. 

• • 
    

    It changes the distance of the pull needed to lift the object.

• It changes the duration needed to lift the object.

• • 
    

    It changes the direction of the force needed to lift the object.

Answer explanation

A simple pulley changes the direction of the force needed to lift an object, allowing you to pull down instead of lifting up, making it easier to raise heavy loads.

Tags

NGSS.MS-ETS1-1

Which advantage does a screw have over a nail? 

• • 
    

    A screw can be inserted with less force than a nail.

• A screw is pushed through a shorter distance.

• • 
    

    A screw allows the force to be applied in a more convenient direction.

• • 
    

    A screw is able to reduce the total amount of work needed.

Answer explanation

A screw can be inserted with less force than a nail due to its helical design, which allows it to grip the material better and requires less effort to drive it in compared to the impact force needed for nails.

Lifting the weight without a pulley requires a force of 400 newtons over a distance of 4 meters. How do these values change when the pulley is applied?

• The force increases, while the distance decreases.

• Both the force and the distance decrease.

• • 
    

    The force decreases, while the distance increases.

• Both the force and the distance increase.

Answer explanation

Using a pulley reduces the force needed to lift the weight because it changes the direction of the force, making it easier. However, the distance over which the force is applied increases, as the rope must be pulled longer to lift the weight.

Tags

NGSS.MS-PS3-5

What is the only function of the pulleys in the diagram?

• to change the amount of energy needed to raise the bricks

• to change the direction of the force applied to raise the bricks

• • 
    

    to change the duration of time to raise the bricks

• • 
    

    to change the mass of the bricks to make it easy to raise

Answer explanation

The pulleys primarily change the direction of the force applied, allowing a person to pull down on the rope to lift the bricks up. This makes it easier to raise heavy objects without changing the energy or mass.

Tags

NGSS.MS-PS2-2

Movers want to get a refrigerator up over a 6-inch step. They place a small ramp on the step to make the task easier. Why are the movers using the ramp?

• The ramp increases the distance that the refrigerator needs to move.

• • 
    

    The ramp reduces the distance that the refrigerator needs to move.

• The ramp reduces the mechanical force needed to move the refrigerator.

• The ramp increases the mechanical force needed to move the refrigerator.

Answer explanation

The ramp reduces the mechanical force needed to move the refrigerator by allowing it to be pushed up the incline rather than lifted straight up, making the task easier for the movers.

Tags

NGSS.MS-ETS1-1

Which unit is used to measure force?

• • 
    

    kilogram

• newton

• • 
    

    joule

• watt

Answer explanation

The correct unit for measuring force is the newton. It is defined as the force required to accelerate a one-kilogram mass by one meter per second squared. The other options (kilogram, joule, watt) measure different physical quantities.