Question

(a) The driver of a car fills the fuel tank with gasoline (petrol).
As the gasoline flows into the fuel tank, the gasoline becomes charged.
(i) State the force that causes the gasoline to become charged.

……………………………………………………………………………………………………………………. 
(ii) State the name and the charge on the particles transferred when the gasoline

becomes charged.
name ………………………………………………………………………………………………………………….
charge ………………………………………………………………………………………………………………..

(b) Some of the gasoline spills onto the hand of the driver.
The gasoline evaporates and the driver’s hand cools down.
Explain this cooling effect.
Use ideas about molecules in your answer.
…………………………………………………………………………………………………………………………………
…………………………………………………………………………………………………………………………………
…………………………………………………………………………………………………………………………………
…………………………………………………………………………………………………………………………… 
(c) (i) During a journey in the car, the car engine transfers 5.8 × 10$^{7}$ J of useful energy to the car.

State the work done on the car by the car engine.
State the unit of your answer.

work done = ………………………………. unit ………………. 

(ii) During the journey, the air in the tyres of the car warms up.
Describe what happens to the motion of the air particles in the tyres as the air warms up.
………………………………………………………………………………………………………………………….
…………………………………………………………………………………………………………………….

(d) The windscreen wipers on the car are powered by an electric motor.
The turning effect on the current‐carrying coil in the electric motor can be increased by increasing the magnetic field strength.
(i) State one other way to increase the turning effect on the coil.

……………………………………………………………………………………………………………………. 

(ii) The moment of a force is a measure of its turning effect.
Complete the sentence to describe how to calculate the moment of a force.
The moment of a force is calculated by multiplying the ……………………….. by the perpendicular distance from the ………………………… .

▶️Answer/Explanation

Ans : 12(a)(i) friction ; 
12(a)(ii) electron ;
     negative ;
12(b) the most energetic molecules escape ;
average speed / energy of remaining molecules is lower ;
12(c)(i) 5.8 × 10$^{7}$ ;
      J ;
12(c)(ii) move faster ; 
12(d)(i) increase current / voltage
     or
    increase number of turns ;
12(d)(ii) force ;
    pivot ;