Pearson Edexcel GCSE Combined Science · P9

Forces and their effects

Revision questions with answers for P9 Forces and their effects in Pearson Edexcel GCSE Combined Science (spec 1SC0). Practise with flashcards, a topic quiz, a random quiz across the course, 5 crosswords, or read every question and answer below.

All questions and answers

Question 1 · Spec P9.1
What is a force?
Answer:
A push or pull arising from interaction between objects.
Question 2 · Spec P9.1
What distinguishes contact and non-contact forces?
Answer:
Contact forces require touching objects; non-contact forces act across a gap.
Question 3 · Spec P9.1
Give three contact-force examples.
Answer:
Normal contact force, friction and tension.
Question 4 · Spec P9.1
Give three non-contact-force examples.
Answer:
Gravitational, electrostatic and magnetic forces.
Question 5 · Spec P9.1
What is a gravitational field?
Answer:
A region where a mass experiences a gravitational force.
Question 6 · Spec P9.1
What is an electrostatic field?
Answer:
A region where an electric charge experiences an electrostatic force.
Question 7 · Spec P9.1
What is a magnetic field?
Answer:
A region where a magnet or suitable magnetic material experiences a force.
Question 8 · Spec P9.1
What creates the normal contact force on a book on a table?
Answer:
Interaction with the table surface, pushing perpendicular to the surface.
Question 9 · Spec P9.1
How does friction act between sliding surfaces?
Answer:
It opposes their relative sliding motion.
Question 10 · Spec P9.1
What force does a taut rope exert on an attached object?
Answer:
Tension, pulling along the rope.
Question 11 · Spec P9.1
How can two objects exert forces without touching?
Answer:
They interact through a field, as in gravity or magnetism.
Question 12 · Spec P9.1
How do interaction forces act on the two objects?
Answer:
As equal and opposite forces acting on different objects.
Question 13 · Spec P9.1
A hand pushes a wall. What is the partner interaction force?
Answer:
The wall pushes back on the hand with equal magnitude and opposite direction.
Question 14 · Spec P9.1
Why does the Earth also experience a force from a falling object?
Answer:
Gravitational interaction produces a force on each object, not only on the falling object.
Question 15 · Spec P9.2
What makes force a vector?
Answer:
Its effect depends on both size and direction.
Question 16 · Spec P9.2
How do weight and mass differ as quantity types?
Answer:
Weight is a vector force; mass is a scalar.
Question 17 · Spec P9.2
How does an arrow represent a force?
Answer:
Its length represents magnitude and its direction shows the force direction.
Question 18 · Spec P9.2
Why must the scale of a force diagram be stated?
Answer:
Arrow lengths must be convertible into force magnitudes.
Question 19 · Spec P9.3 · Higher only
What is a resultant force?
Answer:
A single force with the same overall effect as the forces acting together.
Question 20 · Spec P9.3 · Higher only
Find the resultant of 8 N and 5 N acting right.
Answer:
13 N right.
Question 21 · Spec P9.3 · Higher only
Find the resultant of 12 N right and 7 N left.
Answer:
5 N right.
Question 22 · Spec P9.3 · Higher only
What is the resultant of two opposite 9 N forces on one object?
Answer:
Zero.
Question 23 · Spec P9.3 · Higher only
How can a scale drawing find the resultant of angled forces?
Answer:
Draw vectors head-to-tail to scale; the resultant joins the first tail to the final head.
Question 24 · Spec P9.3 · Higher only
How is the resultant's direction measured on a scale diagram?
Answer:
Use a protractor to measure its angle from a stated reference direction.
Question 25 · Spec P9.3 · Higher only
A resultant arrow is 4 cm at 1 cm = 3 N. Find force magnitude.
Answer:
4 × 3 = 12 N.
Question 26 · Spec P9.3 · Higher only
What does resolving a force mean?
Answer:
Replacing it with two perpendicular components that have the same overall effect.
Question 27 · Spec P9.3 · Higher only
Why do perpendicular components together reproduce one force?
Answer:
Their vector sum equals the original force in both magnitude and direction.
Question 28 · Spec P9.3 · Higher only
How can a scale diagram show equilibrium for three forces?
Answer:
The vectors drawn head-to-tail form a closed shape, giving zero resultant.
Question 29 · Spec P9.4 · Higher only
What belongs on a free-body diagram?
Answer:
Only forces acting on the chosen object, with labelled directions and appropriate relative sizes.
Question 30 · Spec P9.4 · Higher only
Which forces act on a book resting on a horizontal table?
Answer:
Weight downward and normal contact force upward.
Question 31 · Spec P9.4 · Higher only
Why should the force the book exerts on the table be omitted from the book's free-body diagram?
Answer:
That force acts on the table, not on the chosen book.
Question 32 · Spec P9.4 · Higher only
Which forces act on a hanging stationary mass?
Answer:
Weight downward and tension upward.
Question 33 · Spec P9.4 · Higher only
Which forces act on a parachutist descending through air?
Answer:
Weight downward and air resistance upward.
Question 34 · Spec P9.5 · Higher only
What does zero resultant force imply about motion?
Answer:
The object remains at rest or continues at constant velocity.
Question 35 · Spec P9.5 · Higher only
A car travels at constant velocity. Compare driving and resistive forces.
Answer:
They balance, giving zero resultant force.
Question 36 · Spec P9.5 · Higher only
A car's driving force exceeds resistance. What happens?
Answer:
It accelerates in the direction of the resultant force.
Question 37 · Spec P9.5 · Higher only
A falling object's drag becomes equal to weight. What happens to acceleration?
Answer:
Acceleration becomes zero and the object moves at terminal velocity.
Question 38 · Spec P9.5 · Higher only
Why can stationary objects have several non-zero forces acting?
Answer:
The forces can balance so their vector sum is zero.
Question 39 · Spec P9.5 · Higher only
An object has 20 N up and 16 N down. State the resultant.
Answer:
4 N upward.
Question 40 · Spec P9.5 · Higher only
An object has 10 N left, 6 N right and 4 N right. Is it in translational equilibrium?
Answer:
Yes. Horizontal forces sum to zero, assuming other directions are also balanced.
Question 41 · Spec P9.5 · Higher only
Why can two equal forces at right angles fail to balance?
Answer:
Equal magnitude alone is insufficient; they must be opposite in direction to cancel as a pair.
Question 42 · Spec P9.5 · Higher only
Why must all force directions be considered before predicting motion?
Answer:
Different components can cancel or reinforce; one large force alone does not determine the resultant.
Question 43 · Spec P9.10
How does lubrication reduce friction?
Answer:
It reduces direct interaction between moving surfaces, making sliding easier.
Question 44 · Spec P9.10
How does lower friction reduce wasted energy?
Answer:
Less work is done against friction, so less energy transfers to unwanted thermal stores.
Question 45 · Spec P9.10
Give a practical use of lubrication.
Answer:
Oil or grease between moving machine parts, such as bearings.
Question 46 · Spec P9.10
Why can lubrication reduce wear as well as heating?
Answer:
Reduced surface contact decreases frictional damage to the parts.
Question 47 · Spec P9.10
Why is lubrication unsuitable where high grip is needed?
Answer:
Reducing friction can prevent tyres, brakes or other gripping surfaces from working effectively.
Question 48 · Spec P9.10
How could lubrication's effect be compared fairly?
Answer:
Use the same surfaces, load, speed and distance, changing only lubrication and measuring force or energy transfer.
Question 49 · Spec P9.3 · Higher only
A 5 cm arrow represents 25 N. What length represents 40 N?
Answer:
Scale = 5 N/cm; 40/5 = 8 cm.
Question 50 · Spec P9.4 · Higher only
Why should force arrows be labelled by both type and interacting object where useful?
Answer:
It identifies what causes each force and helps prevent mixing forces acting on different objects.

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