Practice Question

1.What is Newton’s Second Law of Motion, and how is it expressed mathematically?

The acceleration of an object is proportional to the resultant force acting on the object, and inversely proportional to the mass of the object. Force = mass x acceleration

2.If the net force acting on an object doubles, what happens to the acceleration?

The acceleration will also double, as acceleration is directly proportional to the force.

3a.What does it mean when an object has a constant acceleration?

A constant acceleration means the object’s velocity changes at a steady rate.

3b.How is this related to the net force?

Uniform accleration occurs when there is a constant resultant force

4.An object of mass 5 kg accelerates at 3 m/s². What is the force acting on the object?

$F=ma$

F=5kg×3m/s²=15N.

5. A 20N force is applied to a 4kg object. What is its acceleration?

acceleration = Force/mass

acceleration = 20/4 = 5m/s²

6.A force of 50N is applied to a box, causing it to accelerate at 2 m/s^². What is the mass of the box?

mass = Force/acceleration

mass = 50/2

mass = 25kg

7.If an object is moving and has an acceleration that is zero, what can you say about the resultant force on the object?

The resultant force is 0N.

8.A cyclist and bike together have a mass of 80kg. If the cyclist pedals with a force of 200N against an air resistance of 50N, what is the net force and resulting acceleration?

Resultant(Net) force: 200−50=150 N

acceleration = force/mass

acceleration = 150/80

acceleration = 1.9m/s²

8.Explain why a heavier object requires a greater force to achieve the same acceleration as a lighter object.

Since F=ma, a larger mass requires a greater force to achieve the same acceleration.

9.Describe how a force vs. acceleration graph would look for a fixed mass.

The graph would be a straight line passing through the origin, with the slope representing the mass.

10.Interpret a velocity-time graph to identify where Newton’s Second Law applies.

Gradient of a velocity time graph is acceleration. If this is a straight line that is not horizontal, it means there is uniform acceleration and so a resultant force is acting on the object.

11.Given a graph of force vs. acceleration, determine the mass of the object.

The mass is the gradient (slope) of the graph

12.What is inertial mass, and how is it defined?

Inertial mass is a measure of how hard it is to change the velocity of an object.

13.Why is inertial mass considered a measure of an object’s resistance to acceleration?

Objects with greater inertial mass require a larger force to achieve the same acceleration as objects with smaller inertial mass.

14.Why does a heavy truck require a larger force to accelerate than a small car?

The truck has a greater inertial mass, so it resists changes in motion more than the car.