Forces and Motion

WJEC

GCSE

Forces and Motion establishes the fundamental relationship between physical interactions and kinematic behavior through Newton's Laws of Motion. Candidates must analyze vector quantities to determine resultant forces and apply the principle of proportionality between force and acceleration. The module requires the mathematical interrogation of distance-time and velocity-time graphs to derive velocity, acceleration, and displacement, extending to the analysis of terminal velocity and the mechanics of braking systems.

Objectives

Exam Tips

Pitfalls

Key Terms

Mark Points

What You Need to Demonstrate

Key skills and knowledge for this topic

Award 1 mark for calculating the gradient of a velocity-time graph to determine acceleration
Credit responses that explicitly state the resultant force is zero when describing objects at constant velocity
Award 1 mark for determining the area under a velocity-time graph to calculate distance travelled
Candidates must substitute correct values into F=ma and provide the final answer with the unit Newtons (N)
Award 1 mark for linking the increase in air resistance to the reduction in resultant force during freefall acceleration

Example Examiner Feedback

Real feedback patterns examiners use when marking

"You correctly identified the formula, but check your unit conversions before substituting."
"Good calculation of the gradient. Now, explain what this value represents in the context of the motion."
"You stated the forces are balanced. To improve, explicitly mention that the resultant force is zero."
"Excellent use of the conservation of momentum. Ensure you clearly state the direction for vector quantities."

Marking Points

Key points examiners look for in your answers

Award 1 mark for calculating the gradient of a velocity-time graph to determine acceleration
Credit responses that explicitly state the resultant force is zero when describing objects at constant velocity
Award 1 mark for determining the area under a velocity-time graph to calculate distance travelled
Candidates must substitute correct values into F=ma and provide the final answer with the unit Newtons (N)
Award 1 mark for linking the increase in air resistance to the reduction in resultant force during freefall acceleration

Examiner Tips

Expert advice for maximising your marks

💡Always show your working for calculations; marks are often awarded for substitution even if the final answer is incorrect
💡When asked to describe motion from a graph, use specific data points from the axes to validate your statement
💡Ensure you distinguish clearly between factors affecting thinking distance (driver state) and braking distance (road/car conditions)
💡For Higher Tier momentum questions, draw a 'before' and 'after' diagram to ensure signs (directions) are correct

Common Mistakes

Pitfalls to avoid in your exam answers

Confusing the gradient of a distance-time graph (speed) with that of a velocity-time graph (acceleration)
Failing to convert time into seconds or speed into m/s before performing calculations
Describing the forces on a falling object as 'equal' without specifying that the resultant force is zero at terminal velocity
Neglecting to include direction when defining vector quantities like displacement or momentum

Key Terminology

Essential terms to know

Newton's Laws of Motion and Inertia

Scalar and Vector Quantities

Kinematic Graph Analysis (Distance-Time and Velocity-Time)

Weight, Mass, and Gravitational Field Strength

Terminal Velocity and Fluid Resistance

Likely Command Words

How questions on this topic are typically asked

Calculate

Describe

Explain

Determine

Compare

Plot

Practical Links

Related required practicals

•{"code":"Specified Practical","title":"Investigation of Newton's Second Law","relevance":"Verifying the relationship between force, mass, and acceleration"}

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