Unit 2 Forces

What kind of friction occurs as a fish swims through water?

• rolling

• static

• sliding

• fluid

As you push a cereal box across a tabletop, the sliding friction acting on the cereal box

• is usually greater than static friction.

• equals the weight of the box.

• acts in the direction of motion.

• acts in the direction opposite of motion.

The weight of a space probe on the surface of Mars is about

• one-third its weight on Earth’s surface

• three times greater than its weight on Earth’s surface

• the same as its weight on Earth’s surface

• nine times greater than its weight on Earth’s surface

According to Newton’s second law of motion, the acceleration of an object equals the net force acting on the object divided by the object’s

• momentum

• velocity

• mass

• weight

In which of the following are action and reaction forces involved?

• when stepping from a curb

• when rowing a boat

• when a tennis racket strikes a tennis ball

• all of the above

What is conserved when two objects collide in a closed system?

• velocity

• acceleration

• speed

• momentum

The gravitational force between two objects increases as mass

• decreases or distance decreases.

• decreases or distance increases.

• increases or distance increases.

• increases or distance decreases.

An open parachute increases air resistance of a falling sky diver by

• increasing surface area.

• decreasing the weight of the diver.

• increasing the terminal velocity.

• reducing fluid friction.

What is the momentum of a 50-kilogram ice skater gliding across the ice at a speed of 2 m/s?

• 48 kg·m/s

• 100 kg·m/s

• 25 kg m/s

• 50 kg

The property of matter that resists changes in motion is called

• gravity

• weight

• friction

• inertia