Newton's Second Law - ScienceKid.org

How does a force actually change motion — and by how much? Newton's Second Law gives us the equation that links force, mass, and acceleration. From bicycle racing to rocket science, this is the rule that makes predictions possible.

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Q1 Question 1 of 10

Newton's Second Law can be summarised as F = ma. What do the letters F, m, and a stand for?

F = friction, m = momentum, a = area F = net force (N), m = mass (kg), a = acceleration (m/s²) F = frequency, m = metres, a = angle F = field strength, m = molecules, a = atoms

Q2 Question 2 of 10

Two identical shopping trolleys are pushed with the same force. One is empty; one is full of groceries. Which accelerates more, and why?

The full trolley — it has more energy stored inside it The empty trolley — it has less mass, so the same force produces a greater acceleration They accelerate equally because the same force is applied The full trolley — gravity helps push it forward

Q3 Question 3 of 10

A 2 kg object is pushed with a net force of 10 N. What is its acceleration?

20 m/s² 5 m/s² 0.2 m/s² 12 m/s²

Q4 Question 4 of 10

A racing car driver wants to accelerate faster. Given F = ma, which two strategies would help?

Decrease engine force and increase mass Increase mass and increase engine force Increase engine force OR reduce the car's mass Increase speed directly without changing force or mass

Q5 Question 5 of 10

What is friction, and in which direction does it always act?

A force that always acts downward due to gravity A contact force between surfaces that always opposes the direction of motion A pulling force that acts in the same direction as motion An electrostatic force between charged particles in the air

Q6 Question 6 of 10

A car engine applies a driving force of 3,000 N. Friction and air resistance together oppose the motion with 1,000 N. What is the net force on the car?

4,000 N forward 1,000 N backward 2,000 N forward 3,000 N forward

Q7 Question 7 of 10

A 5 kg object has a net force of 0 N acting on it. What is its acceleration?

5 m/s² — it accelerates at its own mass 0 m/s² — the object does not accelerate It decelerates to zero speed because the force is zero 1 m/s² — you divide the mass by itself

Q8 Question 8 of 10

In which direction does an object accelerate according to Newton's Second Law?

Always downward, because gravity is always present Opposite to the direction of motion In the same direction as the net force Perpendicular to the direction of the force

Q9 Question 9 of 10

Why does a feather fall more slowly than a bowling ball in air, even though gravity pulls both downward?

Gravity pulls on the bowling ball harder because it is heavier The feather has more inertia because it is lighter Air resistance is much greater relative to the feather's weight, so the net downward force on it is much smaller Feathers are made of a material that repels gravity

Q10 Question 10 of 10

A rocket in space fires its engine and exerts a force of 50,000 N. If the rocket's mass is 5,000 kg, what is its acceleration?

250,000,000 m/s² 0.1 m/s² 10 m/s² 55,000 m/s²

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