Question 1

Newton stated that if a force were applied to an object in space, the resultant acceleration would depend on the

Accepted Answer

Newton's Second Law of Motion states that the acceleration of an object as produced by a net force is directly proportional to the magnitude of the net force, in the same direction as the net force, and inversely proportional to the mass of the object.

Question 2

The strength of gravity on Mars is about 40% of that on Earth. If an astronaut were to visit Mars, what would happen to their mass and weight compared to when they were on Earth?

Accepted Answer

Mass is a measure of the amount of matter in an object and does not change with location. Weight is the force of gravity on an object and would be less on Mars due to its weaker gravity.

Question 3

The strength of gravity on Mars is about 40% of that on Earth. If an astronaut's mass on Earth is 60 kg, what would their weight be on Mars?

Accepted Answer

Weight on Mars = (Weight on Earth) * (Gravity on Mars / Gravity on Earth) = 60kg * 9.8m/s^2 * 0.4 = 235.2 newtons.

Question 4

What is the size of the force a person exerts on Earth compared to the force Earth exerts on that person as they stand on its surface?

Accepted Answer

According to Newton's third law of motion, for every action, there is an equal and opposite reaction. This means that the force a person exerts on Earth is exactly the same as the force Earth exerts on that person.

Question 5

A diver weighing 138 pounds has just dived up and out from the high board and is doing a backflip before starting to descend toward the water. How much force does the diver exert on Earth while doing the backflip?

Accepted Answer

The force exerted by the diver on Earth is equal to the diver's weight, which is 138 pounds, according to Newton's third law of motion, which states that for every action, there is an equal and opposite reaction.

Question 6

The strength of gravity on Mars is about 40% of that on Earth. If an astronaut's mass on Earth is 60 kg, what would their mass be on Mars?

Accepted Answer

Mass remains constant regardless of the location in the universe; it is the weight that changes due to gravity.

Question 7

The mass of an object is a measure of how

Accepted Answer

Mass is a measure of the amount of matter in an object and determines how much force is needed to accelerate it, making D the correct choice.

Question 8

An unbalanced force acting on an object will always cause it to change its

Accepted Answer

An unbalanced force acting on an object will always cause it to change its speed, direction of travel, or both, according to Newton's second law of motion. This is because an unbalanced force results in a net force on the object, causing acceleration, which can manifest as a change in speed, a change in direction, or both.

Question 9

The strength of gravity on Mars is about 40% of that on Earth. If an astronaut were to take a standard red brick to Mars, which property of the brick would be significantly different on Mars than on Earth?

Accepted Answer

The weight of an object is the force with which it is pulled towards a planet, which depends on the local gravity. Since Mars has about 40% of Earth's gravity, the brick would weigh significantly less there, while its mass, color, and volume would remain unchanged.

Question 10

An accelerating body must at all times

Accepted Answer

An accelerating body must have a changing velocity, which encompasses both changes in speed and/or direction. Acceleration is defined as the rate of change of velocity with respect to time, not necessarily an increase in speed or constant motion in one direction.

Question 11

Which of these pairs of forces is an example of an action-reaction pair by Newton's third law?

Accepted Answer

Newton's third law states that for every action, there is an equal and opposite reaction. The force of the dog on the leash and the force of the leash on the dog are equal in magnitude and opposite in direction, making them an action-reaction pair.

Question 12

According to Newton's third law, if a force is acting on an object, then

Accepted Answer

Newton's third law states that for every action, there is an equal and opposite reaction. This means if a force is exerted on an object, another force of the same magnitude but in the opposite direction acts on a different object.

Question 13

An object orbiting the Sun in a circle can be said to be

Accepted Answer

An object in circular orbit is always changing its direction of motion, even if its speed remains constant. This change in direction is a change in velocity, indicating acceleration. This acceleration is centripetal, directed towards the center of the circular path.

Question 14

The Sun exerts a gravitational pull on Earth. Why doesn't Earth fall into the Sun?

Accepted Answer

Earth's angular momentum and velocity in its orbit create a centripetal force that balances the gravitational pull from the Sun, keeping Earth in a stable orbit rather than falling into the Sun.

Question 15

A horse is dragging a loaded sled across a field. Which of these pairs of forces is an action-reaction pair by Newton's third law?

Accepted Answer

Newton's third law states that for every action, there is an equal and opposite reaction. The force of the horse on the sled and the force of the sled on the horse are an action-reaction pair, as they are equal in magnitude and opposite in direction.

Question 16

A rocket that is accelerated by the force from the ejection of large quantities of hot gases represents an example of which physical law originally stated by Newton?

Accepted Answer

The rocket's operation is an example of Newton's third law of motion, which states that for every action, there is an equal and opposite reaction. The ejection of hot gases out of the rocket's engine creates a force (action) that propels the rocket forward, and in response, an equal and opposite force (reaction) is exerted by the rocket on the gases.

Question 17

A person standing on bathroom scales sees a reading of 148 pounds. This person is acted on by

Accepted Answer

The person is acted upon by two forces of equal size but in opposite directions: the gravitational force pulling them down (their weight) and the normal force from the scale pushing them up, which is why the scale shows a reading of 148 pounds.

Question 18

The action and reaction forces referred to in Newton's third law of motion

Accepted Answer

Newton's third law of motion states that for every action, there is an equal and opposite reaction. This means that the action and reaction forces act on different bodies, not the same one.

Question 19

Which of these statements is a correct version of Newton's third law?

Accepted Answer

Newton's third law states that for every action, there is an equal and opposite reaction. This means when object A exerts a force on object B, object B exerts a force of equal magnitude but in the opposite direction on object A.

Question 20

Which of these statements about an asteroid moving in a circular orbit around the Sun is NOT true?

Accepted Answer

Even though the speed of the asteroid remains constant in a circular orbit, its direction changes continuously. Therefore, its velocity, which includes both speed and direction, is not constant. Acceleration occurs due to this change in direction, maintaining the asteroid's circular path.

Quiz 2: Gravitation and the Motion of the Planets