Effects of Forces (Cambridge (CIE) IGCSE Physics)

Newton's first law states that objects with constant velocity will experience no change in their motion unless a resultant force is applied.

Constant velocity refers to motion at a steady speed and in a straight line.

The situation when an object experiences no resultant force when the forces acting on it are balanced, meaning the net force is zero.

The value of the frictional force is equal to the driving force, as both forces are balanced when the car moves at a constant velocity.

Newton's first law of motion states that: objects will remain at rest, or move with a constant velocity unless acted on by a resultant force.

When a non-zero force acts on an object, the object can:

• change its speed

• change its direction

Newton's second law of motion states that the acceleration of an object is proportional to the resultant force acting on it and inversely proportional to the object's mass.

False.

Newton's second law states that acceleration is directly proportional to the object's resultant force, and inversely proportional to its mass.

Newton's first law states that an object's motion will change if acted upon by a resultant force, and Newton's second law describes that change in motion.

The equation for Newton's second law is

Where:

• = resultant force, measured in Newtons (N)

• = mass, measured in kilograms (kg)

• = acceleration, measured in metres per second squared (m/s²)

False.

In the equation , the force and acceleration act in the same direction.

According to Newton's second law, acceleration is inversely proportional to mass, meaning a larger mass will experience smaller accelerations for the same applied force.

According to Newton's second law, increasing the resultant force acting on an object will increase the acceleration of the object by the same factor.

True.

According to Newton's second law, the acceleration of an object is inversely proportional to its mass.

Hooke’s law states that the extension of a spring is proportional to the applied force.

The equation for Hooke's law is

Where:

• = force applied, measured in newtons (N)

• = spring constant, measured in newtons per kilogram (N/m)

• = extension of the spring, measured in metres (m)

False.

Hooke's Law states that the extension of a spring is directly proportional to the applied force.

Hooke's Law describes the relationship between the extension of a spring and the applied force, stating that they are proportional.

The spring constant (k) is the force per unit extension and measures how stiff the spring is.

False.

The spring constant (k) has units of N/m.

The elastic limit represents the point beyond which an object will no longer return to its original length when stretched, violating Hooke's Law.

The green arrow shows the linear portion of the graph. This is the section that obeys Hooke's law, where force and extension are directly proportional.

The green arrow shows the non-linear section of the graph where Hooke's law is not obeyed. Force and extension are no longer proportional.

The red cross represents the limit of proportionality. Beyond this point, force and extension are no longer directly proportional.

Circular motion is the movement of an object along a circular path, where the object's velocity is constantly changing due to the change in direction.

False.

In circular motion, an object's speed may be constant, but its velocity is constantly changing due to the change in direction.

In circular motion, an object's velocity is always changing as it moves along the circular path.

A force causes an object to change direction in circular motion when it acts at 90 degrees to the direction of travel.

The factors that determine the force needed to maintain circular motion depend on the mass of the object, the speed of the object, and the radius of the circular path.

False.

A smaller radius requires a greater force to maintain constant speed in circular motion.

True.

Velocity is defined as the rate of change of displacement.

The two factors that are affected by the size of the radius of an object in circular motion are how large the circular path is and the force required to maintain the motion.

True.

A satellite orbiting a planet is an example of circular motion.

True.

The speed of an object in circular motion will increase if the force is increased providing that the mass and radius remain constant.

False.

The radius of an object in circular motion will decrease if the force is increased providing that the mass and speed remain constant.

True.

For an object in circular motion, an increased mass requires an increased force to keep the speed and radius constant.

Friction is the force between two surfaces that impedes motion and produces heating.

False.

Friction opposes the motion of an object, slowing it down.

True.

Friction causes heating, which raises the temperature of the object and its surroundings.

Friction in solids is created by imperfections on the surfaces of the objects moving over one another.

Fluids are substances that can flow and take the shape of their container. Gases and liquids are fluids.

Drag is the frictional force acting on objects moving through fluids, caused by collisions with the gas or liquid particles.

True.

Air resistance, experienced by objects moving through the air, is a type of friction that slows down their motion.

Air resistance increases the temperature of an object by heating due to the work done against frictional forces as particles collide with the object.

True.

Drag is the frictional force acting on an object as the object moves through a fluid (a liquid or a gas).