Newton's laws

What is inertia?

• the force that opposes motion

• the force of attraction between 2 objects

• an object's tendency to stay in motion or to stay at rest

• a change in an object's speed and/or direction

Answer explanation

Inertia is an object's tendency to stay in motion or to stay at rest. This means that an object will not change its state of motion unless acted upon by an external force, making this the correct definition of inertia.

Tags

NGSS.MS-PS2-2

Which has more Inertia? (and takes more force to move)

• Truck

• Ant

Answer explanation

The truck has more mass than the ant, resulting in greater inertia. More force is required to change the motion of the truck compared to the ant, making the truck the correct choice.

Tags

NGSS.MS-PS2-2

According to Newton’s first law of motion, an object at rest that is not acted on by an unbalanced force will

• remain in motion.

• eventually come to a stop.

• change its momentum.

• remain at rest

Answer explanation

According to Newton's first law, an object at rest will remain at rest unless acted upon by an unbalanced force. Therefore, the correct answer is that it will remain at rest.

A car speeding up, a dog slowing down and person turning around the block are examples of..

• Balanced Forces

• Unbalanced Forces

Answer explanation

The car speeding up, dog slowing down, and person turning indicate changes in motion, which are caused by unbalanced forces. Balanced forces would not result in any change in motion.

Tags

NGSS.MS-PS2-2

If force remains constant, what happens to acceleration if mass is decreased?

• Acceleration decreases.

• Acceleration increases.

• Acceleration remains constant.

Answer explanation

According to Newton's second law (F = ma), if force (F) is constant and mass (m) decreases, acceleration (a) must increase to maintain the equation. Thus, acceleration increases when mass is decreased.

Tags

NGSS.MS-PS2-2

An object is resting on a table, not moving. No forces are acting on the object.

• True

• False

Answer explanation

The statement is false because even if the object is not moving, it is still subject to gravitational force acting downwards and the normal force from the table acting upwards, resulting in a net force of zero.

An object is resting on a table, not moving. The table is exerting an upward force on the object.

• True

• False

Answer explanation

The object is at rest, indicating that the forces acting on it are balanced. The table exerts an upward force, known as the normal force, which counteracts the object's weight, confirming that the statement is true.

Tags

NGSS.3-PS2-1

NGSS.5-PS2-1

What happens to the velocity of an object if the net force acting on it is zero?

• It remains constant.

• It becomes zero.

• It decreases.

• It increases.

Answer explanation

If the net force acting on an object is zero, according to Newton's first law, the object's velocity remains constant. This means it will not speed up, slow down, or change direction.

Tags

NGSS.MS-PS2-2

Which of the following is an example of Newton's third law of motion?

• A book resting on a table

• A ball rolling down a hill

• A rocket launching into space

• A car moving at constant speed

Answer explanation

A rocket launching into space exemplifies Newton's third law, which states that for every action, there is an equal and opposite reaction. The rocket expels gas downward, propelling itself upward.

Tags

NGSS.MS-PS2-1

When a car suddenly stops, passengers tend to lurch forward. This is an example of:

• Acceleration

• Friction

• Inertia

• Gravity

Answer explanation

When a car stops suddenly, passengers continue moving forward due to inertia, which is the tendency of an object to resist changes in its state of motion. This demonstrates how inertia affects passengers in a moving vehicle.