Forces

Question 1

Define friction

Answer 1

Force caused by two surfaces rubbing together

(sliding or trying to slide past eachother can work too)

Question 2

Define weight

Answer 2

Force on an object due to gravity

Question 3

Define air resistance

Answer 3

Friction between an object and the air is moving through

Question 4

Define upthrust

Answer 4

The upward force acting in liquid and gases

Question 5

Define magnetic force

Answer 5

Force between two magnets or between a magnet and an iron or steel object

Question 6

Define electrostatic force

Answer 6

Force between objects which are electrically charged

Question 7

Define tension

Answer 7

Force acting in stretched objects such as strings, ropes or springs

Question 8

Define thrust

Answer 8

A push that accelerates an object in a given direction

Question 9

Define drag

Answer 9

Friction between an object and the fluid (gas or liquid) it is moving through

Question 10

What are drag and air resistance types of?

Answer 10

Friction

Question 11

What are most forces measured in?

Answer 11

Newtons

Question 12

What do we use to measure forces?

Answer 12

A Newton meter

Question 13

State the formula to figure out the weight of an object

Answer 13

Weight (N) = mass (kg) x gravity (m/s2)

Question 14

Explain Hooke’s law

Answer 14

Hooke’s law suggests that the extension of a spring will be directly proportional to the weight of the object added.

Question 15

Explain how a electrostatic force works

Answer 15

Electrostatic force is when an object (usually an insulator) transfers its electrons to another material after rubbing. Due to the fact that there is now more electrons in that material than before the electrons will repel other electrons from other surfaces or materials.

Question 16

Give an example of electrostatic force in action

Answer 16

For example: a balloon may stick on the wall, or attract water towards itself coming from a tap, or make someone’s hair stick up.

Question 17

What is the moment or turning force?

Answer 17

A moment is the force on an object fixed around a pivot point, and when an object of a heavier mass can only balance out one of less mass when it is closer to the picot point.

Question 18

What is a pivot point?

Answer 18

The point where the lever turns

Question 19

What is the lever?

Answer 19

An object which is on the pivot point, which can turn in the direction of the heavier mass

Question 20

What is the load or effort?

Answer 20

The weight trying to push the lever down due to gravity (the effort and the loads are opposite forces trying to push the lever to turn to their side)

Question 21

State the formula to work out a moment

Answer 21

Moment (Nm) = force of object (N) x distance from pivot point (m)

Remember that the force of the object is not the same as the mass!

Question 22

State the formula to work out the circumference of a circle

Answer 22

Circumference (cm) = pi x diameter (cm)

Question 23

True or false? The larger the surface area, the more resistance the object will experience - meaning the longer it takes to fall through or travel through the air (and vice versa)

Answer 23

True

Question 24

What is scientifically classed as a fluid?

Answer 24

Liquids and gases

Question 25

True or false? saltwater has the least upthrust

Answer 25

False - salt wall has the most upthrust, followed by freshwater then air

Question 26

What is the resultant force?

Answer 26

The overall force of an object

Question 27

How can you work out the resultant force of an object?

Answer 27

By subtracting opposite forces from each other, and the resultant force points towards a side with a bigger force to start with (and this is only for opposite forces: right and left, up and down! You cannot calculate the resultant force of an object when the forces aren’t opposite)

Question 28

State four important points for labelling for diagrams

Answer 28

1. Draw all arrows from one point, preferably in the middle 2. The arrow size showed the force size and relative to each other 3. Add the newtons next to the arrow if it is known 4. The arrow direction show the direction that the force is acting in

Question 29

What method can help with formulas?

Answer 29

The speed, distance, and time triangle method

Question 30

What is a balanced force?

Answer 30

A balanced force is when all the force is acting on it are equal

Question 31

What is the effect of a balanced force?

Answer 31

A balanced force can either stay still, or travel at a constant speed (according to Newton’s First Law of Motion)

Question 32

What is an unbalanced force?

Answer 32

An unbalanced force is when all the forces on an object are unequal

Question 33

What are the effects of an unbalanced force?

Answer 33

Unbalanced forces can change three things within an object: 1. Shape 2. Speed or 3. Direction

Question 34

What is a contact force?

Answer 34

A contact force is a force that can only act on an object when they are physically touching or in contact

Question 35

State two examples of a contact force

Answer 35

Friction, tension, thrust, upthrust, air resistance, drag (any two from the list above will work)

Question 36

What is a non contact force?

Answer 36

A noncontact force is a force that can act an object even when they are not touching or not in contact

Question 37

State two examples of a non contact force

Answer 37

Electrostatic force, magnetic force, gravitational pull

Question 38

Clearly distinguish between gravity and weight

Answer 38

Gravity is the acceleration (or push) on an object. Weight is the force on an object due to the push of gravity.

Question 39

What is the Earth’s gravity?

Answer 39

9.8 m/s2 (roughly 10 m/s2)

Question 40

What is the SI units of measurement?

Answer 40

Kilograms (kg)

Question 41

Order these in terms of the most friction: gravel, concrete, sandpaper, marble, carpet

Answer 41

Sandpaper, gravel, concrete, carpet, marble

Question 42

State the formula to figure out the force applied onto a spring

Answer 42

Force of object (N) = spring constant (N/m) x extension (m)

Question 43

What is the spring constant?

Answer 43

The spring constant is how stiff the spring is, or how much force (N) it takes to extend 1 unit (usually meters) of a spring.

Question 44

What is the elastic limit?

Answer 44

When a spring will not follow Hooke’s Law anymore, nor will it return to its original length

Question 45

What must happen so that a moment is balanced?

Answer 45

Anti-clockwise turn force = clockwise turn force

Question 46

What is the gravity on the moon?

Answer 46

1.6 m/s2

Question 47

# Equipment: retort stand and clamp, a spring and a meter ruler State the methods for an experiment using the force tension and Hooke's Law

Answer 47

1. Set up a meter ruler against a retort clamp and stand, then add a spring hanging for the stand 2. Mesure and record the length of the unstretched spring in mm 3. Add 100g mass (or a mass hanger) to the end of the spring 4. Mesure the length of the spring with the mass added, then calculate the extension of the spring by subtracting the original length of the spring from the stretched length 5. Repeat this experiment by adding more 100g masses and calculating the extension