Science Review Grade 6

What force pulls objects toward the centre of the Earth?

• Magnetism

• Friction

• Gravity

• Elastic force

Answer explanation

The force that pulls objects toward the center of the Earth is gravity. It is a fundamental force that attracts masses towards each other, and in this case, it pulls everything towards the Earth's center.

Which type of force occurs when two surfaces rub against each other?

• Gravity

• Friction

• Magnetic force

• Buoyancy

Answer explanation

Friction is the force that occurs when two surfaces rub against each other, opposing their relative motion. It is responsible for slowing down or stopping moving objects, making it the correct answer.

What kind of force is used by magnets to pull or push objects?

• Gravitational force

• Frictional force

• Magnetic force

• Elastic force

Answer explanation

Magnets use magnetic force to attract or repel objects. This force is distinct from gravitational, frictional, and elastic forces, making 'magnetic force' the correct choice for how magnets interact with other materials.

How does an inclined plane make work easier?

• By reducing friction

• By decreasing the force needed to lift an object

• By changing the direction of the force

• By increasing gravity

Answer explanation

An inclined plane reduces the force needed to lift an object by allowing it to be raised over a longer distance at a gentler angle, making it easier to move heavy loads with less effort.

What happens to friction when the surface becomes smoother?

• Friction increases

• Friction decreases

• Friction stays the same

• Friction disappears

Answer explanation

As surfaces become smoother, the microscopic irregularities that cause friction are reduced. This leads to a decrease in friction, making it easier for objects to slide over each other.

What is the main force that opposes motion?

• Gravity

• Friction

• Magnetism

• Buoyancy

Answer explanation

Friction is the main force that opposes motion between surfaces in contact. It acts in the opposite direction to the movement, slowing down or stopping objects, making it the correct answer.

Which force acts in the opposite direction to motion and slows objects down?

• Gravity

• Friction

• Magnetic force

• Elastic force

Answer explanation

Friction is the force that opposes motion between two surfaces in contact. It acts in the opposite direction to the movement, slowing down objects as they slide or roll.

What is an example of gravity acting on an object?

• A ball rolling on the ground

• A book falling off a shelf

• A magnet pulling a nail

• A car being pushed uphill

Answer explanation

Gravity is the force that pulls objects toward each other. A book falling off a shelf is a clear example of gravity acting on an object, as it accelerates downward due to the gravitational pull of the Earth.

What type of force does a magnet use to attract or repel objects?

• Gravitational force

• Frictional force

• Magnetic force

• Elastic force

Answer explanation

A magnet uses magnetic force to attract or repel objects. This force acts on magnetic materials, distinguishing it from gravitational, frictional, and elastic forces.

What kind of simple machine is a seesaw?

• Pulley

• Lever

• Wheel and axle

• Inclined plane

Answer explanation

A seesaw is a type of lever, which consists of a rigid bar that pivots around a fulcrum. When one side is pushed down, the other side rises, demonstrating the principle of leverage.