PSC 5

An astronaut's mass is 80 kg on Earth. What is their mass on Mars?

• 80 kg

• 40 kg

• 20 kg

• 0 kg

Answer explanation

An astronaut's mass remains constant regardless of location. Therefore, their mass on Mars is still 80 kg, the same as on Earth.

The weight of an object depends on:

• Its density only.

• The force of gravity acting on it.

• Its volume only.

• The speed at which it moves.

Answer explanation

The weight of an object is determined by the force of gravity acting on it, which varies depending on the object's location. Density and volume affect mass, but weight specifically relates to gravitational force.

Tags

NGSS.MS-PS2-4

Which force is responsible for free fall motion?

• Magnetic force

• Gravitational force

• Frictional force

• Nuclear force

Answer explanation

The force responsible for free fall motion is the gravitational force. It pulls objects towards the Earth, causing them to accelerate downwards when no other forces, like air resistance, are acting significantly.

Tags

NGSS.MS-PS2-2

NGSS.MS-PS2-4

A skydiver reaches terminal velocity when:

• The force of gravity equals air resistance.

• They stop accelerating.

• They stop falling.

• Both a and b.

Answer explanation

A skydiver reaches terminal velocity when the force of gravity equals air resistance, meaning they stop accelerating. Thus, both conditions (a and b) are correct.

Tags

NGSS.MS-PS2-2

An object at rest will stay at rest unless acted on by:

• Gravity

• An unbalanced force

• Friction

• Velocity

Answer explanation

An object at rest will remain at rest unless acted on by an unbalanced force, as stated in Newton's first law of motion. Gravity and friction can be balanced, while velocity does not apply to stationary objects.

Tags

NGSS.MS-PS2-2

What is the formula for force according to Newton's Second Law?

• F = ma

• F = m/v

• F = mg

• F = mv²

Answer explanation

According to Newton's Second Law, the formula for force is F = ma, where F is force, m is mass, and a is acceleration. This relationship shows how force is directly proportional to both mass and acceleration.

Tags

NGSS.MS-PS2-2

When an object's net force is zero, it is:

• Accelerating

• At rest or moving at constant velocity

• Falling

• Gaining mass

Answer explanation

When the net force on an object is zero, it means there is no change in its motion. Therefore, the object is either at rest or moving at a constant velocity, as per Newton's first law of motion.

According to Newton’s Third Law, for every action, there is:

• No reaction

• An opposite but equal reaction

• A stronger force in the same direction

• A weaker force in the opposite direction

Answer explanation

According to Newton's Third Law, every action has an equal and opposite reaction. This means that for every force exerted, there is a force of the same magnitude but in the opposite direction, making "An opposite but equal reaction" the correct choice.

Tags

NGSS.MS-PS2-1

What unit is used to measure mass?

• Newton

• Kilogram

• Meter

• Joule

Answer explanation

The kilogram is the standard unit of mass in the International System of Units (SI). Unlike the other options, which measure force (Newton), length (Meter), or energy (Joule), the kilogram specifically quantifies mass.

What happens to your weight on the Moon?

• It increases

• It decreases

• It remains the same

• It doubles

Answer explanation

Your weight on the Moon decreases because the Moon's gravitational pull is about 1/6th that of Earth's. This means you would weigh significantly less on the Moon than you do on Earth.

Tags

NGSS.MS-PS2-4

NGSS.MS-PS2-5