P1-P4 Random questions

Question 1

Use the idea of electric fields to explain why two charged objects experience an electrostatic force between them. (3 marks)

Answer 1

• All charged objects have an electric field around them
• It is the interaction of the electric fields which causes a force between the two objects
• Opposite charges attract and like charges repel

Question 2

Suggest one simple demonstration to show electrostatic force in action. (1 mark)

Answer 2

Use a charged rod to pick up paper

Question 3

What is the definition of weight.

Answer 3

The force that gravitation exerts on a body

Question 4

Equation for weight when gravitation field strength is given .

Answer 4

Weight (N) = mass(kg) * gravitational field strength (N/kg)

Question 5

How to work out potential energy ?

Answer 5

Potential energy(J) = mass (kg) * height (m) * gravitational field strength (N/kg)

Question 6

A scientist climbs Mount Everest. He carries a packet of crisps with him to the top of the mountain. At the top of the mountain the crisp packet has expanded.
Explain why.

(4 marks)

Answer 6

• Atmospheric pressure decreases as you climb the mountain because there is less air above pushing down.
• at the top of mountain there is less air pressure in the outside of the packet.
• As bag pressure is bigger than air pressure the crisp packet expands.

Question 7

A student uses a bicycle pump to inflate a tyre. The temperature of the gas increases as the type is inflated.

Explain why

(2 marks)

Answer 7

• apply force on pump to do work on the gas

- kinetic energy of particles increases

Question 8

A simple electric motor can be made by placing a wire loop in a magnetic field.
Explain how rotation is caused when a cell is connected to the wire loop.

Answer 8

• Current flows in the wire loop
• One side of the loop experiences a force downwards
• The other side of the loop experiences a force upwards
• Causing rotation around the axis

Question 9

What happens to the size of the force turning the motor if:

a) a second identical cell was connected in series with the first
b) the number of turns was doubled
c) the number of turns was double and the magnetic field strength was halved

Answer 9

a) Doubles
b) Doubles
c) no change

Question 10

A loaded trolley with a mass of 10kg travels at 10m/s.

What happens to the kinetic energy (KE) of the trolley if the speed doubles and the mass halves.

Answer 10

Kinetic Energy doubles