1. Grade 10 Science Physics: Forces

2. What is Force?
Force is a push or a pull on something.

3. Which of the following objects feels a force?
A soccer ball being kicked
Foot pushes, Gravity pulls
A book sitting on a table
Gravity pulls, Table pushes up
An airplane flying
Gravity pulls, Air pushes back

4. Which of the following objects feels a force?
A rock in deep space
No force, No gravity
The space shuttle orbiting Earth
Gravity pulls
The Earth
Sun’s and moon’s gravity pulls

5. Which of the following objects feels a force?
A calculator sliding across a desk
Gravity pulls, desk pushes back
You, right now
Gravity pulls, chair pushes up
A fish in the ocean
Gravity pulls, air inside pushes up

6. All things at all times on Earth feel one or more forces.
__________ pulls things towards the centre of the earth.
Gravity
__________ pushes against things that are moving.
For example, cars feel air resistance.
Friction
__________ forces push against other forces. For example, a table pushes up on a book.
Normal

7. All things at all times on Earth feel one or more forces.
__________ forces push or pull things that have an electric charge.
Electric
__________ forces push or pull things that are magnetic.
Magnetic
The ________________ force keeps the nucleus inside the atoms together.
nuclear strong
The ________________ force makes atoms change into different atoms.
nuclear weak

8. Try to list as many forces as you can that affect the soccer ball
Sitting on the ground
Gravity, normal from the ground
On the ground getting kicked
Gravity, normal on the ground, push from foot
Flying through the air after being kicked
Gravity, air resistance

9. Try to list as many forces as you can that affect the soccer ball
Rolling on the ground
Gravity, normal from the ground, air resistance, ground resistance
Rolling to a wall and bumping into it
Gravity, normal from ground, normal from wall

10. What is Net Force? Net force makes things change their motion.
Net force = all forces added together

11. 1. A car driving on a straight road at a constant speed of 50 km/hr.
Motion Changing No
Net Force No
2. A car driving on a straight road speeding up.
Motion Changing
Yes
Net Force
Yes

12. 3. A car driving on a straight road slowing down to stop.
Motion Changing
Yes
Net Force
Yes
4. A car stopped at a red light.
Motion Changing No
Net Force No

13. 5. A car driving on a curved road at a constant speed of 50 km/hr.
Motion Changing
Yes
Net Force
Yes
6. A car falling straight down towards the ground faster and faster after going off a cliff.
Motion Changing
Yes
Net Force
Yes

14. 7. A car falling straight down towards the ground at a constant speed of 250 km/hr.
Motion Changing No
Net Force No
8. The car’s parachute starts to open and the car falls straight towards the ground more and more slowly.
Motion Changing
Yes
Net Force
Yes

15. 9. The parachute is fully opened and the car falls straight towards the ground at a constant speed of 30 km/hr.
Motion Changing No
Net Force No
10. Based on your answers to questions 1 to 9, does a car need a net force to move?
NO!!!
11. Based on your answers to questions 1 to 9, what does a net force do?
It causes the car to change its motion.