Newton’s First Law
By the end of this lesson, I will learn what Newton’s First Law states and the effect
is has in everyday scenarios.
Do now:
1. Open the link and complete the questions
2. Write everything that could happen to an object
when a force is applied to it.
2. Forces change the shape, speed or direction of an
object.
By the end of this lesson, I will learn what Newton’s First Law states and the effect
it has in everyday scenarios.
By the end of this lesson, I will learn what Newton’s First Law states and the effect
it has in everyday scenarios.
By the end of this lesson, I will learn what Newton’s First Law states and the effect
it has in everyday scenarios.
By the end of this lesson, I will learn what Newton’s First Law states and the effect
it has in everyday scenarios.
By the end of this lesson, I will learn what Newton’s First Law states and the effect
it has in everyday scenarios.
By the end of this lesson, I will learn what Newton’s First Law states and the effect
it has in everyday scenarios.
So,
• If the forces on the box are balanced the resultant force is zero and the box will remain
at rest or constant velocity.
• If the forces on the box are unbalanced the resultant force is not zero and the velocity
of the box will change.
Newton’s First Law states that if the resultant force acting on an object is zero:
• If it is stationary, it will remain stationary.
• If it is moving, it will continue to move at the same speed and in the same direction (its
velocity won’t change).
This means that if an object changes speed or direction a resultant force must be acting
on it.
By the end of this lesson, I will learn what Newton’s First Law states and the effect
it has in everyday scenarios.
Reaction
force
Weight
1. Add the car’s weight.
2. Is the car moving
downwards?
No
3. What is the force called
that must be balancing
the weight?
By the end of this lesson, I will learn what Newton’s First Law states and the effect
it has in everyday scenarios.
Reaction
force
1. Add the car’s weight.
2. Add the reaction force
Friction and drag
Driving
force
Weight
3. Add the driving force
from the engine
4. What other forces are
there?
By the end of this lesson, I will learn what Newton’s First Law states and the effect
it has in everyday scenarios.
1. Add the driving force
from the engine
Reaction
force
Res
Friction and drag
(smaller than the push)
Driving
force
Weight
2. What other forces are
there, and how big are
they?
Resultant force:
The resultant force is the single force that can replace a number of forces acting on an object.
(depending on their direction, they get added or subtracted)
Any object can be:
stationary
moving
Balanced forces
constant
velocity
Balanced forces
Changing velocity
(accelerating/decelerating)
Unbalanced forces
For the objects in the pictures below;
a) Draw force arrows on the diagram, to show the size and direction of the forces.
b) Label these arrows with the names of the forces.
A stationary duck on a lake
Time: 7 minutes
A football that has been kicked and is
now moving along the ground.
Hot air balloon travelling at a
constant height.
A boy who has jumped in the air.
A tug of war.
A stationary duck on a lake
A football that has been kicked and is
now moving along the ground.
Reaction force
or Normal
Weight
Hot air balloon travelling at a
constant height.
Buoyancy
Weight
A boy who has jumped in the air.
Lift
A tug of war.
Weight
Pull
Weight
Pull
Answer in full, as many questions as you can
Time: 7 minutes
1. How do we represent
forces?
2. What do we measure
forces in?
3. What is meant by
balanced forces?
4. What is meant by
unbalanced forces?
5. When would an
object move left?
6. What is friction?
7. What is a resultant
force?
8. When will a car
accelerate?
9. How does a ball
thrown in space move?
10. Why does the ball
move like this?
11. When does a car
move at a constant
speed?
12. If the resultant force
is zero...
1. How do we represent forces?
2. What do we measure forces
in?
3. What is meant by balanced
forces?
4. What is meant by unbalanced
forces?
Arrows, directions, sizes
Newtons (N)
Forces in opposite directions
that are the same size
Forces in opposite directions
that are different sizes
5. When would an object move
left?
6. What is friction?
7. What is a resultant force?
8. When will a car accelerate?
Force that slows down
movement when two
surfaces touch, in the
direction opposite to the
movement
Overall force acting on an
object, size and direction
When there is a resultant
force present, otherwise the
acceleration is 0
9. How does a ball thrown in
space move?
10. Why does the ball move like
this?
11. When does a car move at a
constant speed?
12. If the resultant force is
zero...
Will continue to move in the
same direction at the same
speed
No opposing force, no
friction, no gravity
When both forces in
opposite directions are
balanced, no resultant force
Either not moving or it is at
constant speed
If the resultant force points
to the left