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GCSE Questions on pressure, buoyancy, upthrust and fluids

Q6. Antonio dropped a piece of modelling clay into oil. The diagram shows the modelling clay just before it was dropped into the oil.

(a) Tick one box to indicate the distance fallen by the modelling clay.

from A to C  
from A to D  
from B to C  
from B to D

[1 mark]

(b) What measuring instrument should be used to measure the distance fallen?

metre rule (or ruler or tape measure)

[1 mark]

(c) Antonio dropped four pieces of modelling clay, each one was a different shape.

For each piece of clay he measured the time taken to fall the same distance through the oil.

He removed each piece of modelling clay from the oil before dropping the next piece.

Suggest one reason why he did this.

He did this so that each piece falls the same distance.

OR

He did this to stop them from building up at the bottom

[1 mark]

(d) Antonio repeated the measurements and calculated mean values. The table shows his results.

Shape
Time taken /s
Drop 1
Drop 2
Drop 3
Mean
Sphere
47
38
41
42
Cube
68
49
57
58
Cylinder
34
37
34
X
Cone
29
23
26
26

 

(i) Calculate the value of X in the table.

34 + 37 +34 = 105

105 ÷ 3 = 35 s

[2 marks]

(ii) Each piece of modelling clay had the same mass.

Which shape had the smallest resistive force acting against it as it fell? (Give one reason for your answer).

The cone had the smallest resistive force acting against as the mean time it took to fall is the lowest (or because it had the most streamlined shape).

[2 marks]

(e) How would the 'time taken to fall' change if the modelling clay was dropped through air instead of through oil?

Time through air would be less.

[1 mark]

(f) The mass of a piece of modelling clay was 50 g

Given that the gravitational field strength = 9.8 N/kg, calculate the weight of the piece of modelling clay.

weight = mass × gravitational field strength

w = mg

m = 50 g = 0.050 kg

w = 0.050 x 9.8

w = 0.49 N

[4 marks]

(g) Weight causes the modelling clay to fall through the oil. Weight is a non-contact force.

Which of the following are also non-contact forces?

Air resistance  
Electrostatic force
Friction  
Magnetic force
Tension  

[2 marks]

[14 Marks TOTAL]