Forces Review 8th Grade Science

Draw a picture that shows an object being acted upon by forces that do not add up to zero.

Different forces-unbalanced. 40N 70 N

Explain why an object would move (ex: a soccer ball being kicked)

Forces are unbalanced so the ball would move.

Which of the following is a contact force Which of the following is a contact force? Gravity Magnetism Friction Electricity

Remember contact means touching, so friction would be the contact force because it occurs as two objects rub together.

A car is traveling down the street and a passenger is holding Starbucks. From what frame of reference is the Pumpkin Spice Latte moving from left to right? Someone watching the car come from the left. Someone watching the car come from the right. Someone in the car.

Someone watching the car come from the left.

When a balanced force acts on a non-moving object, the object will: remain motionless slow down begin moving

remain motionless

To keep a heavy box sliding across a carpeted floor at a constant speed, a person must continually exert force on the box. To keep it moving, the person is overcoming which force? Air resistance drag kinetic friction magnetic force

Kinetic Friction

Give the vocabulary word: Any region in which a physical force has an effect.

Field

Give the vocabulary word: A push or pull exerted on an object in order to change the motion of the object.

FORCE

Give the vocabulary word: A force that opposes the movement of two surfaces that are in contact and moving over each other.

Kinetic Friction

Give the vocabulary word: A force of attraction between two objects that is due to their masses.

Gravity

Give the vocabulary word: A force that resists the start of sliding motion between two surfaces that are in contact and at rest

Static Friction

Give the vocabulary word: A friction like force that opposes the motion of an object in a fluid (like air)

Drag

Which Law states that “acceleration of an object depends on the mass of the object and amount of force applied?

Newton’s 2nd Law (F = ma)

What causes a marble rolling across a carpet to slow to a stop, where as it would continue to go farther on a tile floor?

Friction

What is net force?

The combined forces acting on an object

The third law of motion states what?

For every action, there is an equal and opposite reaction.

Give an example of Newton’s 1st Law of Motion.

A book at rest sitting on the table A book at rest sitting on the table. A ball flying through the air until it hits another force (net).

What is the difference between weight and mass? Do they change?

Weight is how much gravity is pushing on an object Weight is how much gravity is pushing on an object. Mass is how much matter makes up an object. Weight would change if you were to go to space, but mass would not.

Draw an object with two forces acting on the object in the same direction and the net force is equal to 10 N.

8 N 2 N

Draw a situation where there are two forces acting on an object in the opposite direction and the net force is equal to 30 N to the left.

20 N 50 N

If a bowling ball and a tennis ball are dropped from the same height, which will hit the ground first? Explain using one of Newton’s Laws.

Both would hit at the same time when in a vacuum Both would hit at the same time when in a vacuum. The first law is related to this because it states an object in motion stays in motion until another force acts on it (ground).