Force, mass and acceleration (a = (v – u)/t) | Exit Quiz | Oak National Academy

Match the following key terms to their definitions.

• directly proportional

• A relationship where one value is a constant multiple of the other.

• air track

• A track that uses a cushion of air to reduce frictional forces.

• inversely proportional

• A relationship where one value halves each time the other doubles.

• Newton's Second Law of motion

• Acceleration: proportional to force, inversely proportional to mass.

Answer explanation

Air tracks reduce friction using an air cushion. Newtons Second Law states that acceleration is directly proportional to force and inversely proportional to mass. (a ∝ F and a ∝ 1/m).

Which of these factors needs to be kept constant when investigating the effect of force on acceleration using an air track, glider and set of hanging masses?

• the size of the force causing the acceleration

• the mass placed on the hanging mass holder

• the mass of the glider

• the total mass of the system (glider and holder)

• the time the glider accelerates for

Answer explanation

The total mass of the system needs to be the same, so when a mass is taken off the hanger it must be placed onto the glider to conserve the total mass.

Starting with the smallest, sort the following in order of increasing resultant force.

Answer explanation

The correct order is the ball (F = 1.0 kg × 3.0 m/s² = 3.0 N), the sprinter (F = 70 kg × 3.0 m/s² = 210 N), the car (F = 900 kg × 0.5 m/s² = 450 N), the skydiver (F = 60 kg × 10 m/s² = 600 N) then the aeroplane (F = 20 000 kg × 0.1 m/s² = 2000 N).

Calculate the acceleration of a dynamics trolley of mass 0.80 kg when a resultant force of 2.0 N acts on it.

• 0.5 kg

• 2.0 kg

• 12.5 kg

• 500 kg

• 1 250 000 kg

In an experiment, a glider of mass 0.25 kg accelerates along an air track, from rest to a velocity of 1.20 m/s in 0.50 s. What is the size of the resultant force acting on the glider?

• 0.15 N

• 0.30 N

• 0.60 N

• 0.70 N

• 1.20 N