Topic 5 - Forces

Question 1

What is a force?

Answer 1

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

Question 2

What unit is force measured in ?

Answer 2

Newtons (N)

Question 3

Are forces classed as a vector or scalar quantities and why?

Answer 3

-vector
- because they have both magnitude and direction

Question 4

what is a contact force?

Answer 4

the objects are physically touching

Question 5

what is a non- contact force?

Answer 5

the objects are physically separated.

Question 6

Name 4 types of contact forces

Answer 6

-friction,
-air resistance,
-tension
-normal contact force

Question 7

Name 3 non contact forces

Answer 7

gravitational force,
electrostatic force
magnetic force

Question 8

Is air resistance a contact or non-contact force? Explain why.

Answer 8

Air resistance is a contact force. This is because it is due to the physical contact (collisions) between an object and the particles in the air.

Question 9

what are scalars?

Answer 9

quantities with a magnitude (size) only.

Question 10

what are vectors?

Answer 10

describes a movement from one point to another. A vector quantity has both direction. and magnitude. (size).

Question 11

name 4 examples of scalar quantities

Answer 11

-time
-temperature
-speed
-distance

Question 12

Name 4 examples of vector quantities

Answer 12

-velocity
-displacement
- acceleration
-momentum
-force

Question 13

What is meant by the term equilibrium?

Answer 13

when the forces acting on an object are all balanced, so the resultant force is 0

Question 14

What is an elastic object?

Answer 14

one that regains its shape when the forces demorming it are removed

Question 15

Fill in the gaps:

When an elastic object is ______________ the energy which caused it to deform is stored as ______ __________ which is released when the force is _________

Answer 15

-deformed
- elastic energy
- removed

Question 16

What is hookes law?

Answer 16

the extension of a spring is directly proportional to the force applied, provided its limit of proportionality is not exceeded
F=Ke

Question 17

What is the method for the hookes law practical (6 steps)?

Answer 17

1. hang the spring to the clamp and add a splint so its easier to read the length
2. check that the splint is horizontal. take a reading on the ruler(lenght of unstretched spring at weight 0.0N)
3. hook the 100g mass hanger on the bottom of the spring. (1N)
4. take a reading of the length of the spring
5. add further masses(100g each time) and measure and record the length of the spring for at least 8 times
6. calculate the extension.by subtracting unstretched spring lenght from each length recording

Question 18

What is an objects spring constant?

Answer 18

a measure of how many Newtons of force it would require to stretch (or compress) the object by 1 metre. It has the units
N/m.

Question 19

Fill in the blank:
Objects with a _____________ spring constant are more stiff, so they require_____force to stretch.

Answer 19

Objects with a higher spring constant are more stiff, so they requiremoreforce to stretch.

Question 20

what does each symbol represent in this equation (hookes law)?
𝐹=𝑘e

Answer 20

Fis the force applied to the spring,𝑘is the spring constant, and𝑒is the extension.

Question 21

If you stretch an object too much it can pass its ‘elastic limit’ (also known as the ‘limit of proportionality’).
At this point what will happen to the object?

Answer 21

It will start deforming inelastically

Question 22

Fill in the blank:
objects with a __________ spring constant are more elastic so they require _____ force to stretch

Answer 22

lower
less

Question 23

What is the equation to work out the elastic potential energy of an object?

Answer 23

𝐸𝑒=1/2𝑘𝑒²

Question 24

what do the symbols in this equation represent?
𝐸𝑒=1/2𝑘𝑒²

Answer 24

𝐸𝑒 (elastic potential energy J)
𝑘 (spring constant N/m)
𝑒² (extention m)

Question 25

In a graph representing hookes law, The gradient of the straight part of the graph tells us the:

Answer 25

spring constant

Question 26

In a graph representing hookes law, The area under the curve tells us the:

Answer 26

Elastic potential energy 

Question 27

In a graph representing hookes law, The point where the line goes from straight to curved is referred to as the:

Answer 27

Limit of proportionality  or Elastic limit

Question 28

What is a moment?

Answer 28

the turning effect of a force around a fixed pivot

Question 29

What is the formula for moment?

Answer 29

Moment (NM)= force(F) x Distance from pivot (m)

Question 30

What would happen to an object if the forces are balanced and the resultant force is 0?

Answer 30

the object will stay in the same state of motion

Question 31

What is the resultant force of an object?

Answer 31

the single overall force acting on an object

Question 32

What two things does the size of a moment depend on?

Answer 32

-size of force - perpendicular distance between force and pivot

Question 33

What is the equation that links weight mass and gravity?

Answer 33

Weight (w) = Mass (m) x gravity (g)

Question 34

What is the equation that links pressure force and area?

Answer 34

Pressure (Pa) = force (N) / area (m²)

Question 35

How can you increase the pressure on a given point in a fluid?

Answer 35

increase the height of the fluid above the point

Question 36

The pressure in a liquid depends on: (2 things)

Answer 36

-density of liquid - depth

Question 37

What is the unit for pressure?

Answer 37

pascals (Pa)

Question 38

What is the formula for pressure in a liquid?

Answer 38

Pressure (n/m²) = density x gravity x height

Question 39

True or false: air pressure is equal in all directions

Answer 39

true

Question 40

What is air pressure caused by?

Answer 40

the force of air gas particles bumping into things

Question 41

What is upthrust?

Answer 41

the upward force that a fluid exerts on a body floating in it

Question 42

An object floats when its weight is _______ to the _____________ provided by the liquid

Answer 42

equal upthrust

Question 43

An object sinks when its weight is __________ than the __________ provided by the fluid

Answer 43

greater upthrust

Question 44

Pressure in a gas is caused by particles ____________. the more frequent collisions and the greater their force, the ___________ the pressure

Answer 44

colliding greater

Question 45

IS distance a scalar or vector quantity and why?

Answer 45

-scalar - it only has a magnitude and is a measure of how far an object has travelled

Question 46

IS displacement a scalar or vector quantity and why?

Answer 46

- vector - has magnitude and direction

Question 47

What is the equation that links speed distance and time?

Answer 47

speed (m/s) = distance/ time

Question 48

What is the equation that links velocity displacement and time?

Answer 48

velocity (m/s) = displacement/ time

Question 49

what is acceleration?

Answer 49

the rate of change in velocity

Question 50

What is acceleration measured in ?

Answer 50

m/s²

Question 51

What is the equation for acceleration if given the time?

Answer 51

acceleration = change in velocity / time taken

Question 52

What is the equation for acceleration if distance is given?

Answer 52

acceleration = final velocity² - initial velocity²

Question 53

As the velocity of a falling object increases, the air resistance:

Answer 53

increases

Question 54

Terminal velocity is reached when:

Answer 54

The resultant force is zero and The weight has the same magnitude as the air resistance

Question 55

What does newtons 1st law state?

Answer 55

if forces acting on an object are balanced then if it is still it will stay still and if it is moving it will keep moving at a constant speed in a straight line

Question 56

what does newtons 2nd law state?

Answer 56

A resultant force will cause an object to accelerate in the direction of the force. the acceleration is directly proportional to the force and inversley proportional to the mass Force = mass x acceleration

Question 57

What does newtons 3rd law state?

Answer 57

for every action there is an equal and opposite reaction however the force mut be of the same type

Question 58

What is momentum?

Answer 58

the tendency of an object to keep moving in the same direction

Question 59

Is momentum scalar or vector?

Answer 59

vector

Question 60

What is the equation that links momentum (kg m/s) mass and velocity?

Answer 60

momentum= mass x velocity

Question 61

What does the conservation of momentum state?

Answer 61

in a 'closed system' the total momentum before an event is equal to the total momentum after the event