Units (Solids, Liquids and Gases)
4 marks · NormalThe atmosphere exerts a pressure of about 100,000 Pa at Earth's surface. A glass window has an area of 0.50 m².
Calculate the force exerted on the outside of the window by the atmosphere.
Describe why you do not notice this large force acting on the window in daily life.
Work this out on paper, then compare with the answer and worked solution below. With a free account you can submit written answers for marking.
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(a) 50,000 N · must show Correctly uses F = p × A
(b) There is also air pressure inside the room, so the forces on both sides are balanced; there is no net force on the window. · must show Pressure acts on both sides, Forces balance/no net force
Common mistakes: Wrong area usage
Show mark scheme and worked solution
Marking points
M1 (a) · 1 mark · Uses F = p × A with correct values.
A1 (a) · 1 mark · Correct answer in newtons (within tolerance).
B1 (b) · 1 mark · States there is air pressure inside the room as well.
B2 (b) · 1 mark · Mentions that the forces are balanced or there is no net effect.
Worked solution
a) F = p × A = 100,000 Pa × 0.50 m² = 50,000 N.
b) There is also air inside the room pressing outward with the same pressure, so the forces balance and there is no noticeable net force on the window.