Laws of Force and Motion

Laws of Motion

A Review

Force

This is a push or pull on an object

Multiple Choice

What is the unit for FORCE?

• N (Newtons)

• lbs (pounds)

• g (grams)

• m/s (meters per second)

Newton's First Law of Motion

The first law states that an object at rest will stay at rest and an object in motion will remain in motion at a constant velocity unless acted upon by an unbalanced force.

Forces can be balanced or unbalanced

When a force is balanced, it will move with a constant velocity (staying still or moving at the same speed)

When a force is unbalanced, it will accelerate in the direction of the larger force.

Net force is the combination of all the forces acting on an object. If the forces are going in the same direction they can be added on top of each other.

Multiple Choice

Balanced or Unbalanced?

• Balanced 
• Unbalanced

Multiple Choice

Forces that have a net force of zero

• Balanced force

• Unbalanced force

Multiple Choice

What is the net force?

• 10 N
• 0 N
• 25 N
• 1 N

Multiple Choice

When Izzy and Zoe pull on the rope with the same amount of force, the forces are _____.

• increased

• unbalanced

• balanced

• decreased

The first law of motion

is also called the law of inertia. The more mass an object has, the more inertia something has, REGARDLESS OF HOW FAST IT IS GOING.

The second law of motion

states that the force of an object is equal to the product of its mass and its acceleration

As force grows, mass or acceleration can grow.

However, if you are keeping the same force, as mass grows, acceleration will decrease or as acceleration increases, mass will decrease.

Multiple Choice

A force of 40 N acts upon a 2 kg block. Calculate the acceleration of the object.

• 20 m/s²

• 20 m/s

• 80 m/s²

• 80 m/s

Multiple Choice

An object with a mass of 100 kg is observed to accelerate at the rate of 5 m/s2. Calculate the force required to produce this acceleration.

• 20N

• 500 M/S

• 500 Kg

• 500N

The third Law of Motion

states that for every action, there is an equal and opposite reaction. In other words, for every action force, there is an equal and opposite reaction force that occurs.

Multiple Choice

Stacy is rowing a boat. She wants the boat to move forward. According to Newton's Third Law, in which direction should she move her paddle in the water?

• Backwards

• Above her head

• Forward

• East

Multiple Choice

A rocket pushes exhaust 10, 000 N. Without any other forces acting on the rocket, how much force does the rocket go forward?

• 15,000 N
• 1,000 N
• 10, 000 N

Multiple Choice

A baseball player bats a ball with a force of 1,000 N. The ball exerts a reaction force (without any additional forces action on it) against the bat of...

• Less than 1, 000 N
• 1,000 N
• More than 1,000 N

Multiple Choice

An archer shoots an arrow. The action force is the bowstring against the arrow, the reaction force is...

• Air resistance against the bow

• the arrow's push against the bowstring

• the grip of the archer's hand on the bow