AQA GCSE Physics
AQA GCSE Physics 4.5.1.4 Resultant Forces Exam Questions
Free AQA GCSE Physics exam questions for 4.5.1.4 Resultant Forces, with a mark scheme for every pack. Covers resultant force from forces in a line, free body diagrams, scale drawings, resolving forces and equilibrium.
4.5.1.4 Resultant Forces exam questions
2 question packs 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 AQA GCSE Physics 4.5.1.4 Resultant Forces
This AQA GCSE Physics section covers how several forces on an object combine into a single resultant force. All students calculate the resultant of forces acting along a line. Higher tier only content includes free body diagrams, using vector diagrams (scale drawings) to find the resultant of two forces at an angle, resolving a single force into two components, and showing that forces are in equilibrium. It is examined on Paper 2 and leads into Newton's laws. Examiners test arithmetic with directions and accurate scale drawings.
What you need to know
- Resultant force A number of forces acting on an object may be replaced by a single force that has the same effect as all the original forces acting together. This single force is called the resultant force.
- Forces in a line Add forces acting in the same direction; subtract forces in opposite directions. The resultant acts in the direction of the larger total.
- Zero resultant If the resultant force is zero, the forces are balanced. The object is either stationary or moving at constant velocity.
- Free body diagrams (Higher tier only) Use free body diagrams to describe qualitatively examples where several forces lead to a resultant force on an object, including balanced forces when the resultant is zero.
- Scale drawings (Higher tier only) Draw two forces to scale, tip to tail, and the resultant is the arrow from the start of the first to the end of the second. Measure its length and angle.
- Resolving and equilibrium (Higher tier only) A single force can be resolved into two components at right angles that together have the same effect. If an object is in equilibrium, the force vectors drawn tip to tail form a closed shape.
Common mistakes in 4.5.1.4 Resultant Forces
- Adding forces that act in opposite directions. Subtract them and give the direction of the resultant.
- Saying zero resultant means the object must be stationary. It could be moving at a constant velocity.
- Drawing scale diagrams without stating the scale, or measuring the angle from the wrong line.
- Missing the direction from the answer. Resultant force is a vector, so give magnitude and direction.
Try three 4.5.1.4 Resultant Forces exam-style questions
1. A box has a 50 N force pulling it to the right and a 20 N friction force acting to the left. Calculate the resultant force. (2 marks)
Show the mark scheme answer
50 minus 20 = 30 N; to the right.
2. Higher tier: Two forces of 3.0 N and 4.0 N act on an object at right angles. Determine the magnitude of the resultant force. (2 marks)
Show the mark scheme answer
Using a scale drawing (or Pythagoras): resultant = square root of (3.0^2 + 4.0^2); = 5.0 N.
3. A car is moving at constant speed on a straight road. Explain what this tells you about the forces acting on it. (2 marks)
Show the mark scheme answer
The resultant force is zero; driving force equals the total resistive forces (friction and air resistance), so the forces are balanced.
4.5.1.4 Resultant Forces FAQs
What does AQA GCSE Physics 4.5.1.4 Resultant forces cover?
It covers finding the resultant of forces in a line and, for Higher tier, free body diagrams, scale drawings, resolving forces and equilibrium.
Which parts of resultant forces are Higher tier only?
Free body diagrams, vector scale drawings for forces at an angle, resolving a force into components and the closed vector diagram for equilibrium are Higher tier only.
What equipment do I need for scale drawing questions?
A sharp pencil, a ruler and a protractor. Choose a sensible scale, draw tip to tail, and state the scale and your measured values.
