Contact and Non-Contact Forces

Question 1

What is a scalar quantity?

Answer 1

-a physical quantity that only has magnitude (size) and not direction
-this means scalar quantities can be measured with numbers

Question 2

what are some examples of scalar quantities?

Answer 2

speed, distance, mass, temperature and time

Question 3

what is a vector quantity?

Answer 3

a quantity that has both magnitude and direction

Question 4

what are some examples of vector quantities?

Answer 4

force, velocity, displacement, acceleration and momentum

Question 5

how are vectors usually represented visually?

Answer 5

-they are represented with arrows
-the length of the arrow shows the magnitude while the direction of the arrow shows the direction of the quantity

Question 6

Are these bikes travelling at the same speed?

Answer 6

-Yes
-here speed is the scalar quantity and the length of the arrows show the magnitude
-since the length of the arrows are the same both bikes are travelling at the same speed

Question 7

Do these bikes have the same velocities?

Answer 7

-No
-Here, velocity is the vector quantity meaning it shows both magnitude and direction
-since the arrows show the bikes are travelling at different directions they don’t have the same velocities

Question 8

What is a force?

Answer 8

a push or pull on an object caused by its interaction with something

Question 9

What are the two types of forces?

Answer 9

Contact and Non-Contact forces

Question 10

Define contact forces and provide examples.

Answer 10

-Contact forces require physical contact between objects
-e.g. friction, air resistance, tension in ropes and normal contact force

Question 11

Define non-contact forces and provide examples.

Answer 11

-contact forces do not require physical contact between objects.
-e.g. magnetic force, gravitational force and electrostatic force

Question 12

What is an interaction pair?

Answer 12

-An interaction pair consists of two forces that are equal in magnitude and opposite in direction, acting on two interacting objects
-e.g. when you push a box, the box exerts an equal and opposite force back on you.

Question 13

Give an example of how non-contact forces can play out.

Answer 13

-the Sun and the Earth are attracted to each other by the gravitational force (this is a non-contact force)
-An equal but opposite force of attraction is felt by both the Sun and the Earth meaning they are interaction pairs

Question 14

Give an example of how contact forces can play out.

Answer 14

-A chair exerts a force on the ground, whilst the ground pushes back at the chair with the same force (the normal contact force)
-Equal but opposite forces are felt by both the chair and the ground (interaction pairs)