P8 Forces in balance

Question 1

What is a scalar quantity?

Answer 1

only has a size (magnitude)

Question 2

What is a vector quantity?

Answer 2

has both a size and direction

Question 3

What is a force?

Answer 3

a push or pull that acts on an object due to the interaction with another object

Question 4

Is force a vector or scalar quantity?

Answer 4

vector

Question 5

What is a contact force?

Answer 5

when objects are physically touching (e.g., friction, air-resistance, tension, normal contact force)

Question 6

What is a non-contact force?

Answer 6

when objects are physically separated (e.g., gravitational, electrostatic, magnetic)

Question 7

What is the same about the interaction pair of forces when two objects interact with each other?

Answer 7

the forces are the same size

Question 8

What is different about the interaction pair of forces when two objects interact with each other?

Answer 8

forces are in opposite directions

Question 9

What is the size of the resultant force on an object if the forces on it are balanced?

Answer 9

zero

Question 10

What is the centre of mass?

Answer 10

the point through which the weight of an object can be considered to act

Question 11

What can you say about clockwise and anticlockwise moments on a balanced object?

Answer 11

sum of all the clockwise moments about any point = sum of all the anticlockwise moments about that point

Question 12

What does Newton’s First Law say?

Answer 12

the velocity of an object will only change if a resultant force is acting on it

Question 13

What is the resultant force on a stationary object?

Answer 13

zero

Question 14

What is the resultant force on an object moving at a steady speed in a straight line?

Answer 14

zero

Question 15

What does Newton’s Third Law say?

Answer 15

when two objects interact they exert equal and opposite forces on each other