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CIE iGCSE Co-Ordinated Science P1.7 Pressure Exam Style Questions Paper 2

Question

A rectangular block weighs 1200 N and has the dimensions shown.

What is the minimum pressure that the block can exert on the ground by standing on one of its faces?

A. \(1.0 N/cm^2\)
B. \(8.0 N/cm^2\)
C. \(10 N/cm^2\)
D. \(15 N/cm^2\)

▶️ Answer/Explanation
Minimum pressure occurs when the block rests on its face with the largest area, since \(P = \frac{F}{A}\) and pressure is inversely proportional to area.
The largest face has dimensions \(15\text{ cm} \times 10\text{ cm} = 150\text{ cm}^2\).
So the minimum pressure is \(\frac{1200\text{ N}}{150\text{ cm}^2} = 8.0\) N/cm².
Answer: (B)

Question

A solid block of weight 14 N rests on a horizontal table. The pressure on the table due to the block is 70 Pa.

What is the area of the surface of the block in contact with the table?

A. \(0.20\text{ m}^2\)  
B. \(5.0\text{ m}^2\)  
C. \(98\text{ m}^2\)  
D. \(980\text{ m}^2\)

▶️ Answer/Explanation
Pressure is given by \(P = \frac{F}{A}\), so rearranging gives \(A = \frac{F}{P}\).
Substituting values: \(A = \frac{14}{70} = 0.20\text{ m}^2\).
Answer: (A)

Question

The diagram shows a cuboid box resting on the ground. The dimensions of the box are shown.

The pressure on the ground due to the weight of the box is \( 50\ Pa \).

What is the weight of the box?

A. 5.0 N
B. 10 N
C. 250 N
D. 500 N

▶️ Answer/Explanation
The base of the box in contact with the ground has an area \( A = 0.50\ m \times 0.40\ m = 0.20\ m^2 \).
Pressure is defined as \( P = \dfrac{F}{A} \), so rearranging gives \( F = P \times A \).
Substituting the values, \( F = 50\ Pa \times 0.20\ m^2 = 10\ N \), which is the weight of the box.
Answer: (B)

Question

A brick has a mass of \(1.5\,\text{kg}\). It rests on the ground and the area of contact with the ground is \(0.030\,\text{m}^2\).

A stack of such bricks is made by placing the bricks on top of each other, as shown.

The pressure on the ground due to the stack must not exceed \(5700\,\text{Pa}\).

What is the maximum number of bricks that can be made into such a stack?

(gravitational field strength \(= 10\,\text{N/kg}\))

A. 11
B. 12
C. 114
D. 256

▶️ Answer/Explanation
Weight of \(n\) bricks \(= n \times 1.5 \times 10 = 15n\,\text{N}\).
Using \(P = \frac{F}{A}\): \(5700 = \frac{15n}{0.030}\), so \(15n = 171\), giving \(n = 11.4\).
Since the pressure limit must not be exceeded, the number of bricks must be rounded down to the nearest whole number.
Answer: (A)

Question

A force of 10 N is applied to a piston of area 0.10 m2, causing a pressure. This pressure is transmitted through a fluid to a piston of area 2.0 m2.

What is the force on this piston?

A. 2.0 N
B. 20 N
C. 200 N
D. 2000 N

▶️ Answer/Explanation
Pressure is calculated using \( P = \dfrac{F}{A} \), so the pressure created is \( \dfrac{10}{0.10} = 100 \ \text{Pa} \).
In a hydraulic system this pressure is transmitted equally throughout the fluid to the second piston.
Rearranging \( F = P \times A \) for the larger piston gives \( F = 100 \times 2.0 = 200 \ \text{N} \).
Answer: (C)
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