Physics #3

Mass

The amount of matter in an object; will not change based on gravity

Weight

A measure of force of gravity on an object; will change based on gravity

Frictional force

The force that resists movement across a surface

Dynamic / kinetic friction

Force of Friction between surfaces in motion; result of surfaces moving over one another.

Static friction

Force of friction between surfaces NOT in motion; result of surfaces adhering to each other; strongest form of friction

Sliding friction

Form of Kinetic/dynamic friction

Rolling friction

Form of Kinetic/dynamic friction; weakest type of friction

Inertia

The tendancy to remain unchanged (Newton’s 1st Law)

Acceleration

The increase (+) or decrease (-) in an object’s motion

Velocity

The direction and a rate at which an object is moving

Explain why the boulder does not move. While there may be a variety of reasons for this, explain how friction is affecting the motion of the boulder.

The boulder will not move across the groud becuase the girl cannot overcome the force of static friction. While the girl applies a force, the rock applies a force back on the girl. Simce the girl cannot overcome the amount of friction, the boulder will not move.

Why is the person not able to move the objects? Include ideas about balanced/unbalanced forces in addition to static friction.

The person is unable to exert a force strong enough to overcome static friction, thus, the object remains stationary (Balanced forces)

Why is the person able to move the object?

The person is able to exert a force strong enough to overcome static friction, thus, the object moves (Unbalanced forces).

How do you calculate an object’s mass (g) to Newtons (N)?

Divide the mass by 100

How do you calculate an object’s force (N) to mass (g)?

Multiply the force by 100

If a golf ball has a mass of 1211.75 grams, what is the force exerted on it in Newtons?

12.1175 N

If a textbook has a mass of 815.2 grams, what is the force exerted on it in Newtons?

8.152 N

If the force exerted on a pencil bag is 1.125248 N, what is the mass in grams?

112.5248 g

If the force exerted on a desk is 973.787 N, what is the mass in grams?

97378.7 g

Newton's First Law

An object in motion will remain in motion unless acted upon by an unbalanced force

Newton's Second Law

The force of an object is the mass multiplied by the acceleration

Newton's Third Law

Every action will have an equal and opposite reaction

How much force is needed to accelerate a 45 kg skier at a rate of 9 m/s?

405 N

What is the acceleration of a 25 kg object pushed with a force of 600 newtons?

24 N

A force of 370 N is applied to an object that accelerates at a rate of 5 m/s. What is the mass of the object?

74 kg

An object has an acceleration of 9 m/s. If the mass of this object were tripled, what would it’s new acceleration (m/s) be?

3 m/s

An object has an acceleration of 10 m/s. If the mass of this object were halved (½), what would it’s new acceleration (m/s) be?

20 m/s

An object has an acceleration of 8 m/s. If the net force was doubled and the mass were halved, what would it’s new acceleration (m/s) be?

32 m/s