P1.5 - Forces

Question 1

What can forces produce change in on an object? [3]

Answer 1

• size
• shape
• motion

Question 2

What is friction? [3]

Answer 2

• the force between two surfaces that may prevent relative motion and produce heating

Question 3

What mediums does friction act along? [2]

Answer 3

• liquid
• gas

Question 4

When does friction act? [2]

Answer 4

when an object is moving through a liquid or gas

Question 5

What’s an example of friction acting against a gas? [1]

Answer 5

air resistance

Question 6

What are forces measured in? [1]

Answer 6

newtons (N)

Question 7

What is a force? [2]

Answer 7

the pull or push of an object that attempts to change it’s motion, shape or size

Question 8

What are examples of forces: [4]

Answer 8

• physically pushing or pulling an object
• magnets pushing or pulling
• electric charges pushing and pulling
• gravitational forces pulling objects together

Question 9

When are magnitudes of forces added together? [1]

Answer 9

when forces are going in the same direction

Question 10

What does it mean if the acceleration is 0? [4]

Answer 10

• means speed is not changing
• DOES NOT MEAN IT’S STAYING THE SAME
• it is travelling at the same speed
• neither accelerating nor deccelerating

Question 11

Which things are in the same direction? [2]

Answer 11

the resultant force and the acceleration

Question 12

What is the spring constant? [1]

Answer 12

force per unit extension

Question 13

What is terminal speed/velocity? [1]

Answer 13

when acceleration is equal to 0 and the object begin to fall down at a constant speed

Question 14

What happens if the total force applied to an object is 0? [1]

Answer 14

object won’t change it’s motion and is equilibrium

Question 15

What is the description of moment of a force? [2]

Answer 15

the turning effect brought on a body due to application of force

Question 16

What is moment of a force? [2]

Answer 16

the product of the force and perpendicular distance from pivot to line of action of the force

Question 17

What is the formula for moment of a force? [2]

Answer 17

moment = force x perpendicular distance from the pivot

Question 18

What is the unit for the moment of a force? [1]

Answer 18

newton metre (n.m)

Question 19

When is an object in equilibrium? [1]

Answer 19

when there is no resultant force and no resultant moment

Question 20

Which ways can a moment rotate? [2]

Answer 20

clockwise and anti-clockwise

Question 21

If the moment is anti-clockwise, what do you use? [1]

Answer 21

+

Question 22

If the moment is clockwise, what do you use? [1]

Answer 22

-

Question 23

What is the principle of moments? [3]

Answer 23

if a body is not to rotate, the net clockwise moment on it must equal the net anti-clockwise moment

Question 24

What is the centre of gravity? [2]

Answer 24

it is the point on a body where the whole of the weight is assumed to be acting

Question 25

If the base area of an object is thicker/bigger, what happens to the stability? [1]

Answer 25

it is more stable and better stability

Question 26

How does distance from the ground affect stability? [2]

Answer 26

the closer the centre of gravity is to the ground the more stable the object is

Question 27

What is the limit of proportionality? [2]

Answer 27

the load after which the extension will not increase linearly with the load