p8 - forces in balance

Question 1

define quantity

Answer 1

anything that can be given a numerical value

Question 2

define magnitude

Answer 2

• size of quantity
• e.g: distance of 5m has a higher magnitude than distance of 2m

Question 3

define scalar

Answer 3

• describes quanitites that only have a magnitude
• e.g: speed

Question 4

define vector

Answer 4

• descibes quantities with magnitude AND a specific direction

Question 5

define a force

Answer 5

• a vector quantity
• pushes or pulls acting on an object
• has size and direction
• result of objects interacting with eachother

Question 6

define contact forces

Answer 6

for these to act, the interacting objects have to be physically touching

Question 7

define non-contact forces

Answer 7

for these to act, interacting objects don’t have to be physically touching

Question 8

define resultant force

Answer 8

single overall force acting on an object

Question 9

list scalar quantities

Answer 9

distance
speed
mass
temperature
pressure
volume
work

Question 10

list vector quantities

Answer 10

displacement
velocity
acceleration
force
weight
momentum

Question 11

give 4 examples of contact forces

Answer 11

1) friction
2) air resistance
3) tension
4) the normal contact force

Question 12

give 3 examples of non-contact forces

Answer 12

1) gravitational force
2) electrostatic force
3) magnetic force

Question 13

why are free-body diagrams useful?

Answer 13

they help us show all forces acting on an object

Question 14

why is it useful to show magnitude and direction in a diagram?

Answer 14

• forces are vector values
• arrow points in direction
• length refers to magnitude

Question 15

how are forces represented?

Answer 15

using vector diagrams

Question 16

how do you represent resultant force on a diagram?

Answer 16

• combine the arrows by appropriately adding or subracting them

Question 17

in which circumstances would the resultant force be zero?

Answer 17

• when forces acting on an object are equal in magnitude and opposite in direction
• forces are balanced

Question 18

what impact does a resultant force of zero have on an object?

Answer 18

has no impact, movement will not change

Question 19

when would you use vector diagrams?

Answer 19

to break down a single force into two forces acting at right angles to each other

Question 20

what is the parallelogram rule used for?

Answer 20

used to find resultant force when forces don’t act in the same line

Question 21

describe the parallelogram rule

Answer 21

watch freesciencelessons video to check knowledge on this

Question 22

define ‘work done’

Answer 22

• the measure of how much energy is transferred when a force makes an object
• always involves transfer of energy
• scalar quantity

Question 23

define a joule

Answer 23

• the unit joule (J) is how energy transfer by work done is measured
• 1 joule = 1 newton metre
• this means that 1 J is
  the amount of work done when a force of 1 N causes an object to move 1 m

Question 24

define distance

Answer 24

• how far an object moves
• scalar quantity (no direction)

Question 25

define displacement

Answer 25

distance in a certain direction

Question 26

define friction

Answer 26

contact force resulting when two object move past and touch eachother

Question 27

how can amount of work be calculated?

Answer 27

W = Fs
work done (J) = force (N) x distance (m)

Question 28

what happens when work is done against friction?

Answer 28

• an energy transfer to heat is caused
• raises temperature of the object and surroundings

Question 29

what is newton’s first law?

Answer 29

if resultant force of an object is zero,
- stationary objects stay stationary
- moving objects keep moving at same velocity

Question 30

define stationary

Answer 30

not moving, resultant force of zero

Question 31

define inertia

Answer 31

the tendency of objects to stay at the same speed or stay stationary

Question 32

what is newton’s second law?

Answer 32

• objects accelerate if there is a resultant force acting on them
• amount of acceleration is proportional to magnitude of resultant force and inversely proportional to the mass of an object

Question 33

what is newton’s third law?

Answer 33

when objects interact, the force they cause to react to each other are equal and opposite

Question 34

define intertial mass

Answer 34

a measurement of an object’s resistance to changes in motion until enough external force is applied

Question 35

give the resultant force equation

Answer 35

F = m a
resultant force (N) = mass (kg) x acceleration (m/s squared)