Q: On an inclined plane, the force of gravity $$mg$$ can be split into two components. What are these components?

$$mg \cos \theta ($$perpendicular) and $$mg \sin \theta ($$parallel)

Question 1

According to Newton's Third Law, when a hammer strikes a nail, what is the reaction force?

Accepted Answer

The force of the nail pushing back on the hammer

Question 2

Which statement best describes Newton's Third Law?

Accepted Answer

For every action, there is an equal and opposite reaction

Question 3

A cannon fires a cannonball. If the force exerted on the cannonball is $$F$$, what is the force exerted on the cannon?

Accepted Answer

$$F$$

Question 4

Why does a cannonball accelerate more than the cannon when fired, even though the forces are equal?

Accepted Answer

The cannonball has much less mass than the cannon

Question 5

Given the equation $$F = ma$$, if the same force $$F is $$applied to two objects of different masses, $$m_1$$ and $$m_2$$, which object will have the greater acceleration?

Accepted Answer

The object with smaller mass

Question 6

When analyzing forces on an orange and a cart system, why don't the action and reaction forces cancel each other out?

Accepted Answer

They act on different objects

Question 7

A skier pushes off the ground with her poles. What is the reaction force according to Newton's Third Law?

Accepted Answer

The ground pushes back on the skier with an equal and opposite force

Question 8

If a person stands on ice and pushes against a wall, what happens according to Newton's Third Law?

Accepted Answer

The wall pushes back on the person with an equal and opposite force

Question 9

On an inclined plane, the force of gravity $$mg$$ can be split into two components. What are these components?

Accepted Answer

$$mg \cos 	heta ($$perpendicular) and $$mg \sin 	heta ($$parallel)

Question 10

A block of ice slides down a frictionless incline. What is the direction of the normal force $$N as $$the incline becomes steeper?

Accepted Answer

The normal force becomes more horizontal

Question 11

If you push a friend on a sled and they push back with an equal force, what determines which one accelerates more?

Accepted Answer

The one with less mass will accelerate more

Question 12

Which of the following is NOT an example of Newton's Third Law?

Accepted Answer

A ball falling freely under gravity

Question 13

If a person jumps off a boat onto a dock, what happens to the boat?

Accepted Answer

The boat moves in the opposite direction

Question 14

When a skier moves down a slope, which force component is responsible for her acceleration down the slope?

Accepted Answer

$$mg \sin 	heta$$

Question 15

If two ice skaters push off against each other, what can be said about the forces and accelerations involved?

Accepted Answer

The forces are equal and opposite, but the accelerations depend on their masses

Question 16

A block rests on an inclined plane. At equilibrium, what is the relationship between the resultant of $$N$$ and $$mg$$?

Accepted Answer

The resultant of $$N$$ and $$mg is $$equal and opposite to friction

Question 17

Which of the following best explains why action and reaction forces do not cancel each other out?

Accepted Answer

They act on different objects

Question 18

A person pulls a sled with a rope at an angle. Which vector component of the force helps move the sled forward?

Accepted Answer

The horizontal component

Question 19

If a force $$F is $$applied to two objects, one with mass $$m$$ and one with mass $$2m$$, what is the ratio of their accelerations?

Accepted Answer

$$2:1$$

Question 20

When a skier moves down an inclined plane, how do you find the resultant of the gravitational force and the normal force?

Accepted Answer

By using the Pythagorean theorem on the vector components

Newton's Third Law of Motion: Study Notes

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