Newton's Laws of Motion

Newton's Laws of Motion Review

October 30, 2020

Sir Isaac Newton

1642-1727

Multiple Select

Sir Isaac Newton studied the following disciplines:

• Physics

• Astronomy

• Mathematics

• Aeronautics

Multiple Choice

The law of gravity was discovered when...

• an apple hit Sir Isaac Newton's head.

• Sir Isaac Newton saw an apple fall from a tree.

• Sir Isaac Newton hypothesized that the Earth revolves around the sun.

• Sir Isaac Newton threw an apple in the air and let it drop to the ground.

First Law of Motion

*If an object is at rest, it stays at rest unless acted upon by an unbalanced force.

*If an object is in motion, it stays in motion unless acted upon by an unbalanced force.

*An object is at rest if the net force is zero.

*Changes in motion come from unbalanced forces.

Multiple Select

An empty shopping cart is pushed along a grocery store aisle at constant velocity. Find the cart’s weight and the friction force if the shopper produces a force of 40.0 newtons between the wheels and the floor, and the normal force on the cart is 105 newtons.

• Cart's Weight: -40.0 N

• Cart's Weight: -105 N

• Friction Force=-40.0 N

• Friction Force=-105 N

Multiple Choice

While the cart is moving along an aisle, it comes in contact with a smear of margarine that had recently been dropped on the floor. Suddenly the friction force is reduced from -40.0 newtons to -20.0 newtons. What is the net force on the cart if the “pushing force” remains at 40.0 newtons?

• 20.0 N

• -20.0 N

• 60.0 N

• -60.0 N

Second Law of Motion

*The acceleration of an object is directly related to the force on it

*The acceleration of an object is inversely related to the mass of the object

*You need more force to move or stop an object with a lot of mass (or inertia) than you need for an object with less mass.

*acceleration=Force/mass

*a=F/m

Multiple Choice

You know the mass of an object and the force applied to the object to make it move. Which of Newton’s laws of motion will help you calculate the acceleration of the object?

• 1st Law of Motion

• 2nd Law of Motion

• 3rd Law of Motion

Multiple Choice

What is the acceleration of a 2,000.-kilogram truck if a force of 4,200. N is used to make it start moving forward?

• 2.1 m/s²

• 0.48 m/s²

• 8,400,000 m/s²

Multiple Choice

How much force is needed to accelerate a 68-kilogram skier at 1.2 m/s²?

• 57 N

• 0.018 N

• 82 N

Third Law of Motion

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

*Action/Reaction Law

*F_A=-F_B

_*Collision

*Action/Reaction Law

Open Ended

You dribble a basketball while walking on a basketball court. List and describe the pairs of action-reaction forces in this situation.

Multiple Choice

A 0.14-kilogram baseball is thrown in a straight line at a velocity of 30. m/s. What is the momentum of the baseball?

• 0.0047 kg*m/s

• 4.2 kg*m/s

• 214 kg*m/s

Multiple Choice

Another pitcher throws the same baseball in a straight line. Its momentum is 2.1 kg · m/s. What is the velocity of the ball? (m=0.14 kg)

• 0.294 m/s

• 0.067 m/s

• 5 m/s

• 15 m/s

Happy Halloween!!

Be careful. Be safe. Make Good choices. :)