Newton's Law Review

Newton's Laws Review

​Newton's 1st Law

​Objects maintain their same state of motion - AT REST or MOVING AT A CONSTANT VELOCITY - unless acted on by an unbalanced force.

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Unbalanced forces result in an ACCELERATION.

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​Also known as the Law of INTERTIA

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​Newton's 1st Law

​Inertia is related directly to an object's mass. The more mass, the more inertia.

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​The more inertia, the more the object wants to maintain it's current state of motion - AT REST or MOVING AT A CONSTANT VELOCITY

​Finding net force

​Add (and subtract) forces in the horizontal.

​Add (and subtract) forces in the vertical.

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​Do you get a net force of 0 N? No acceleration.

​Do you get a net force of anything other than 0 N? ACCELERATION!

Multiple Choice

What is the net force?

• 17 N Right
• 3 N Right
• 3 N Left
• 17 N Left

Multiple Choice

What is the net force?

• 15 N

• 5 N to the left

• 5 N to the right

• 15 N left

Multiple Choice

What is the net force?

• 38 N to the left

• 38 N to the right

• 2 N to the left

• 2N to the right

Multiple Choice

What is the net force?

• 6 N to the right

• 9 N to the right

• 9 N to the left

• 15 N to the left

Multiple Choice

What is the net force?

• 25 N

• 10 N down

• 5 N up

• 10 N up

​Newton's 2nd Law

​F = ma

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​If a certain amount of force is applied to a small mass, that mass will experience a large acceleration.

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​If that same amount of force is applied to a larger mass, that mass will experience a small acceleration.

Multiple Choice

If the man pushes with an equal amount of force, which object will accelerate more?

• Car because it has more mass

• Lawnmower because it has less mass

• Car because it has less mass

• Lawnmower because it has more mass

Multiple Choice

When force is 20 N, mass is 5 kg, what is acceleration?

F = ma

• 25 m/s²

• 100 m/s²

• 5 m/s²

• 4 m/s²

Multiple Choice

Will it take more force to push an empty shopping cart or a shopping cart that is full?

• The empty shopping cart

• They will take the same amount of force

• The full shopping cart

• Depends on what is in the full shopping cart

Multiple Choice

An object accelerates 8 m/s² when a force of 40 newtons is applied to it. What is the mass of the object?

• 4 kg

• 20 kg

• 0.2 kg

• 5 kg

Multiple Choice

(Using F_net=ma), What net force is required to accelerate a car at a rate of 2 m/s² if the car has a mass of 3,000 kg?

• 6,000 N

• 1,500 N

• 3,002 N

• 2,998 N

Multiple Choice

(Use F_net=ma). Use the diagram to determine the net force, assume the object is accelerating at a rate of 3 m/s², and determine the object's mass?

• 3 kg

• 5 kg

• 60 kg

• 75 kg

Multiple Choice

(Use F_net=ma). Use the diagram to determine the net force, assume the object is accelerating at a rate of 2 m/s². What amount of mass does the object have?

• 2 kg

• 4 kg

• 6 kg

• 8 kg

​Newton's 3rd Law

​For every force there is an equal and opposite force.

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​Equal in MAGNITUDE (how many Newtons of force)

​Opposite in DIRECTION

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​ALL forces come in pairs. The forces don't cancel out because they are acting on DIFFERENT objects!

​In this example, the swimmer would be accelerated forward by the equal force because her mass is smaller than the wall (F= ma)

Multiple Choice

Two people are skateboarding. If person 1 has a larger mass than person 2 and person 1 pushes person 2, how much would this affect their movement?

• Mass will have no affect.

• They will accelerate backwards the same.

• Person 1 will accelerate more, but both will move.

• They will both accelerate back, but person 2 will move more.

Multiple Choice

A semi truck and a Volkswagen (small car) traveling at the same speed have a head on collision. Which statement is correct?

• The impact force is greater on the Volkswagen.

• The impact force is greater on the semi truck.

• The impact force is less on the semi truck.

• The impact force is equal for both.

Multiple Choice

Newton's 3rd Law of motion states that....

• A object in motion/rest stays in motion/rest until it is acted upon by an unbalanced force.

• Force is equal to the mass and the acceleration of an object.

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

Multiple Choice

How do forces act on an object?

• They usually act alone

• They act in pairs

Multiple Choice

When a cannon fires a cannonball we observe Newton's third law. Which is the reaction force?

• The cannon moving forward

• the cannon moving backwards

• the cannonball moving backwards

• The cannonball moving forward

Multiple Choice

A book rests on a table.  The force of gravity pulls down on the book with a force of 20 newtons. What prevents the books from accelerating downward ?   

• The table presses back up on the book with an equal and opposite force of 20 newtons.

• The table presses back up with a force greater than 20 Newtons

• The tale and the book together are accelerating downwards at 9.8 m/sec2

• The inertia of the book holds it up

Multiple Choice

A baseball bat hits a baseball with a force of 100 Newtons. What is the force and its direction exerted by the ball on the bat?

• 100 Newtons, same direction

• 100 Newtons, opposite direction

• 200 Newtons, opposite direction

• 200 Newtons, same direction

Multiple Choice

The units of force are:

• Joules

• Newtons

• Newtonmeters

• Newtons per meter squared

​g is the acceleration due to gravity.

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On Earth that is 9.8 m/s²​

Multiple Choice

What is acceleration due to gravity on Earth?

• 98 m/s²

• 9.8 m/s²

• 0.98 m/s²

Multiple Choice

If a bike has a mass of 10.5 kg, how much does it weigh on Earth?

• 102.9 N
• 1.07 N
• 10.5 N
• 0.93 N

Multiple Choice

The Mars Rover Curiosity weighs 8810.2 N on Earth. Determine Curiosity's mass.

• 899 kg
• 86,339.96 kg
• 0.001 kg
• 8810.2 kg

Multiple Choice

If a 75 kg TV is taken to Venus, where it weighs 665 N, what is acceleration due to gravity on Venus?

• 8.87 m/s²

• 49,875 m/s²

• 0.11 m/s²