1. What is a force?
What 3 things can forces do?
Label the forces acting on this car.
Can you identify the interaction pairs?
Forces Y7
Forces can be balanced or unbalanced. The size of the arrow tells you which force is bigger or smaller. For each of the diagrams, draw and label 2 force arrows.
Name each of these contact forces:
f_______ is greatest on r________ surfaces.
u________
a__ _______
Car accelerating
The larger the surface area the _________ the force.
A parachute falling
Name each of these non-contact forces:
Car at constant speed
Object floating on water
Object staying floating in the middle of water
_________
_________
_________
The closer the object the ___________ the force

2. Gravity, Weight and Mass
Hooke’s Law and Extension
What is Hooke’s Law?: __________________
______________________________________
Data interpretation:
M___________ measures how much material an object is made of. It is measured in k__________________.
W________ measures the force of gravity on an object. Because w_________ is a force, it is measured in N_______________.
_______ never changes. _______ changes because it is a force affected by the size of gravity; the bigger the mass, the ________ the weight.
Extension of spring (cm)
Gravitational field strength, mass and weight
Weight (N) = mass (kg) x gravitational field strength (N/kg)
Complete the table:
Which planet has the smallest g?
Looking at the g for Jupiter, what can you deduce about the mass (size) of Jupiter compared to the mass of Earth?
Weight (N)
Planet
Your mass (kg)
Gravitational field strength (N/kg)
Your weight on the planet (N)
Mercury
3.7
Earth
 50kg
10.0
Jupiter
 1155
Neptune
11.0
Pluto
0.7
What is the extension of the spring at 2.6N?
What force is required to extend the spring by 12cm?
Up to 6N, does the spring follow Hooke’s law? Explain.
After 7N, what happens? Why?