OCR GCSE Physics A (Gateway)
OCR GCSE Physics A P2.3 Forces in Action Exam Questions
Free OCR GCSE Physics A exam questions for P2.3 Forces in Action, with a mark scheme for every pack. Covers Stretching and deforming objects, Hooke's law, energy stored in springs, weight, gravitational field strength, moments, levers and gears.
P2.3 Forces in Action exam questions
1 question pack of real past exam questions, each with its mark scheme. Do not stop after a few: answer as many as you can without notes, then mark every answer with the mark scheme. The more questions you do, the more quickly you will spot how examiners ask about each idea.
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About OCR GCSE Physics A P2.3 Forces in Action
P2.3 completes the P2 Forces chapter of OCR Gateway Physics A. It covers how forces deform objects elastically or plastically, the linear relationship between force and extension for a spring, and the energy stored in a stretched spring. You need to describe the practical investigating force and extension and interpret force-extension graphs. The topic also covers weight, mass and gravitational field strength, and how gravitational field strength differs on other planets. Separate physics content includes moments, levers and gears as force multipliers. Examiners often ask you to find a spring constant from a graph, calculate stored energy and apply the principle of moments.
What you need to know
- Deformation Stretching, bending or compressing needs more than one force. Elastic deformation is reversed when the forces are removed; plastic deformation is not.
- Hooke's law Force exerted on a spring = spring constant x extension (F = kx), up to the limit of proportionality.
- Energy in a spring Energy stored in a stretched spring = 1/2 x spring constant x (extension)^2, which equals the area under the linear part of a force-extension graph.
- Practical Hang masses from a spring, measure extension against a ruler at eye level, and plot force against extension. The gradient of the straight section is the spring constant.
- Weight and gravity Weight = mass x gravitational field strength. Gravitational field strength on Earth is about 10 N/kg and is smaller on the Moon.
- Moments Moment = force x perpendicular distance from the pivot. For balance, the sum of clockwise moments equals the sum of anticlockwise moments.
- Levers and gears Levers and gears act as force multipliers. A small gear driving a larger gear makes it turn more slowly with a larger moment.
Common mistakes in P2.3 Forces in Action
- Using the stretched length instead of the extension. Extension = new length - original length.
- Applying F = kx beyond the limit of proportionality.
- Forgetting to square the extension in the energy equation, or forgetting the half.
- Saying mass changes on the Moon. Mass stays the same; weight decreases because g is smaller.
- Using the distance along a lever rather than the perpendicular distance from the pivot to the line of action of the force.
Try three P2.3 Forces in Action exam-style questions
1. A spring has a spring constant of 200 N/m and is stretched by 0.050 m. Calculate the force applied and the energy stored. (4 marks)
Show the mark scheme answer
F = k x x = 200 x 0.050; = 10 N; energy = 1/2 x k x x^2 = 0.5 x 200 x 0.050^2; = 0.25 J.
2. An astronaut has a mass of 70 kg. Calculate their weight on the Moon, where g = 1.6 N/kg. (2 marks)
Show the mark scheme answer
Weight = mass x g = 70 x 1.6; = 112 N.
3. A 300 N load is 0.20 m from the pivot of a lever. Calculate the effort needed 1.2 m from the pivot on the other side. (3 marks)
Show the mark scheme answer
Clockwise moment = anticlockwise moment; 300 x 0.20 = F x 1.2; F = 60 / 1.2 = 50 N.
P2.3 Forces in Action FAQs
What does OCR GCSE Physics A (Gateway Science) P2.3 Forces in Action cover?
It covers deformation, Hooke's law, energy in springs, weight and gravitational field strength, moments, levers and gears.
Which paper is P2.3 examined on?
Topics P1 to P4 are assessed on Paper 1 (Foundation) or Paper 3 (Higher), alongside practical skills.
How do I find a spring constant from a graph?
Plot force on the y-axis and extension on the x-axis, then calculate the gradient of the straight-line section; make sure extension is in metres to get k in N/m.
