3AB-Forces Flashcard (2024)

Front

If Earth's radius decreases (mass unchanged), your weight would ______.

Back

increase

Answer explanation

If the radius of Earth decreases while mass remains constant, gravitational force increases due to the inverse square law. Thus, your weight would increase.

Front

A planet with half Earth's mass and radius. An apple's weight compared to Earth would be _____?

Back

zero

Answer explanation

The weight of an object is determined by the gravitational force, which depends on mass and radius. With half the mass and half the radius, the gravitational force is reduced, leading to zero weight for the apple on this planet.

Front

Gravitational force between two massive spheres:

Back

Depends inversely on the square of the distances between them.

Answer explanation

The gravitational force between two massive spheres is indeed an attraction and depends on their masses. However, the correct choice highlights that it also depends inversely on the square of the distance between them, as per Newton's law of gravitation.

Front

Two objects move apart. The force between them _____ as they get farther.

Back

decreases

Answer explanation

As two objects move away from each other, the gravitational or electrostatic force between them decreases due to the inverse square law. Therefore, the correct answer is that the force decreases.

Front

Effect of reducing Earth's mass to 0.5 on gravity:

Back

Halved.

Answer explanation

The force of gravity is directly proportional to mass. If Earth's mass is reduced to 0.5, the gravitational force would also be halved, making the correct answer: The force of gravity would be halved.

Front

Effect of tripling distance on gravitational force between two objects.

Back

One-ninth as strong.

Answer explanation

According to Newton's law of gravitation, the gravitational force is inversely proportional to the square of the distance between two objects. If the distance is tripled, the force becomes 1/(3^2) = 1/9, or one-ninth as strong.

Front

Doubling an object's mass while keeping distance constant affects gravitational force how?

Back

It doubles.

Answer explanation

According to Newton's law of universal gravitation, the gravitational force is directly proportional to the masses of the objects. If the mass of one object is doubled, the gravitational force also doubles, while the distance remains unchanged.

Front

Gravitational force between two objects with doubled masses:

Back

Four times stronger.

Answer explanation

The gravitational force is calculated using F = G(m1*m2)/r^2. If both masses are doubled, the new force becomes F' = G(2m1*2m2)/r^2 = 4G(m1*m2)/r^2, which is four times stronger.