GCSE Physics, 4.5- Force.

What is meant by ‘Scalar quantities’. [1 mark]

Quantities that have magnitude.

What is meant by ‘Vector quantities’. [1 mark]

Quantities that have magnitude and direction.

Name the force acting which is labeled by F in the figure. [1 mark]

Tension.

Name the force acting which is labeled by F in the figure. [1 mark]

Friction.

Name the force acting which is labeled by F₁ in the figure. [1 mark]

Air resistance.

Name the force acting which is labeled by F₂ in the figure. [1 mark]

Weight.

Name the force acting which is labeled by F in the figure. [1 mark]

Normal contact force.

A man pushing a box to the left.

It create 40 N to the left.

It create 4 N to the right.

Calculate the result force. [2 marks]

36 N to the left.

What is meant by ‘elastic deformation’.[1 mark]

Elastic material return to orginal shape when force removed.

Explain why elastic material change shape when apply more than one force. [2 marks]

• Force used to do work.

• Elastic potential energy stored in the object.

• Work is done.

What is meant by ‘moment of force’. [1 mark]

Turing effect of the force.

Gear A is connected to Gear B.

Gear B is two times larger than gear A.

If we rotate gear B one time.

Describe what will happen. [3 marks]

• Gear B has two times more moment than gear A.

• The force will be apply on gear A.

• Gear A will rotate twice.

Person A is 60 kg.

Person B is 45 kg.

Explain why the seesaw is balance. [3 marks]

• Person B is further from pivot.

• Cause Person B create more clockwise moment to seesaw.

• Which is the same as person A.

A ping pong ball is thrown to the water.

A ping pong ball is mostly made of air in the inside.

Explain what will happen when ping pong ball is thrown to the surface of water. [4 marks]

• Ping pong ball is less dense than water.

• Ping pong ball only displace small volume of water.

• Cause upthrust equal to the weight.

• Float high.

A ball has the same density as water.

Explain what will happen when the ball is thrown to the surface of water. [3 marks]

• The ball displace its own volume of water.

• In order to upthrust equal to the weight of the ball.

• Float, but the surface of the ball is at the same surface of water..

What is Newton’s first law about. [2 marks]

If the resultant force is zero, then stationary object remain stationary or object moving at the same velocity.

What is Newton’s second law about. [2 marks]

Acceleration is directly proportional to resultant force and indirectly proportional to mass.

What is Newton’s third law about. [2 marks]

When two object interact, the forces they exert on each other are equal and opposite.

Skydiver jump off from the aeroplane.

Skydiver will use parachute.

Explain what happen to the force acting before using parachute. [5 marks]

• When skydriver jump off, only has weight acting.

• Accelerate toward the ground.

• Air resistance will slow down the acceleration.

• As velocity increase, air resistance increase.

• Overtime, air resistance and weight will balance and velocity constant.

Skydiver jump off from the aeroplane.

Skydiver will use parachute.

Explain what happen to the force acting after using parachute. [5 marks]

• When parachute opened, it increase surface area.

• Air resistance increase and decelerate.

• As air resistance decrease, velocity decrease.

• Overtime, air resistance and weight balance.

• Velocity constant.

Describe the energy changes taking place when a vehicle brakes. [2 marks]

• Friction between brake and wheel.

• Cause kinetic energy transferred to thermal energy in the brake.

State 2 the potential danger the large deceleration of vehicle. [2 marks]

Brake overheat and loss control of the vehicle.