forces

Question 1

explain vector quantity + example

Answer 1

they have magnitude and direction ( force velocity acceleration, momentum , displacement)

Question 2

explain scalar quantity + example

Answer 2

only magnitude , no direction (speed distance, time mass temperature)

Question 3

how are vectors shown

Answer 3

arrows, length of arrow shows magnitude, direction shows direction of quantity

Question 4

force

Answer 4

push of pull on an object caused by an interaction with something

Question 5

contact force

Answer 5

2 objects need to be touching for force to act (air resistance , friction, tension in rope)

Question 6

non contact force

Answer 6

objects dont need to touch for force to act (magnetic force, gravitational, electrostatic)

Question 7

interaction pair of forces

Answer 7

pair of forces equal and opposite - act on 2 interating objects

Question 8

interaction pair of forces (non contact)

Answer 8

earth and sun ( attracted by a gravitational force ) equal but opposite force of attraction

Question 9

interaction pair of forces (contact)

Answer 9

chair exerts force on ground , ground pushes chair with the same force - equal but opposite force felt by ground and chair

Question 10

graviational force

Answer 10

force of attraction between masses , on surface of a planet it makes everything fall to the ground and gives everything a weight

Question 11

mass

Answer 11

amount of stuff or matter in an object - same value anywhere in all locations

Question 12

weight

Answer 12

force acting on an object due to gravity- pull of gravitational force on object - force caused by gravitational field around earth

Question 13

what does gravitational field strength vary with

Answer 13

location- its stronger the closer you are to the mass causing the field, stronger for larger masses

Question 14

what does weight of object depend on

Answer 14

strength of gravitational field strength at location of object - weight of object changes with location

Question 15

example of how weight can vary

Answer 15

object on moon will weigh less on moon-1.6 n- than earth because gfs on moon is less than gfson earth-9.8n-

Question 16

how and what is weight measured in

Answer 16

measured in newtons with calibrated spring balance or newtonnmeter - measured from centre of mass- for uniform object, it will be at the centre of the object

Question 17

what is mass measured in

Answer 17

kilograms, with a mass balance - mass is not force

Question 18

how to calculate weight

Answer 18

mass x gravitational field strength (weight and mass is directly proportional)

Question 19

explain what free body diagram shows

Answer 19

size of arrows show relative magnitude of forces. directions show the direction of the forces acting on the object

Question 20

resultant force

Answer 20

overall force on a point or object- if you have a number of forces acting at a single point , you can replace them with single force which has the same effect as all the original forces all together - this single force is known as the resultant force

Question 21

how is overall effect of forces found

Answer 21

if they all are parallel , effect is found by adding those going in same direction - those going in an opposite direction (consider vertical and horizontal directions separately)

Question 22

what happens when a resultant force moves an object

Answer 22

work is done- when a force moves an object through a distance , energy is transferred and work is done on the object
to make an object move a force must be applied . the thing applying the force needs a source of energy, the force does work to move the object and energy is transferred from one source to another

Question 23

example of energy transfer through forces

Answer 23

you push something along rough surface, work is done against frictional forces, energy is transferred to kinetic energy store of object bc it is moving, energy is transferred to thermal energy store(due to friction) causing overall temperature of object to rise

Question 24

how to calculate work done

Answer 24

force x distance is work done
one joule of workis done when a force of one newton causes an object to move a distance of one metre (1 JOULE IS 1 NEWTON METRE)

Question 25

how to use scale drawings to find resultant force

Answer 25

1- start by drawing a scale drawinf of the forces acting 2- sensible scale e.g. 1n-1cm 3- draw resultant from tail of first arrow to tip of last arrow 4- measure length of resultant with ruler , use scale to find force in N 5- use protractor to measure direction as a bearing (clockwise from north )

Question 26

what does it mean if an object is in equilibrium

Answer 26

forces on it are balanced, if all forces combine to give a resultant force of 0 the object is in equilibrium

Question 27

how would you find a missing force given that the object is in equilibrium

Answer 27

draw the forces you know , join end of last force to the start of the first force , the line is the missing force so you can measure its size and direction

Question 28

how do you split a force into components

Answer 28

forces at awkward angles can be split into 2 components at right angles to each other - acting togrther these components have the same effect as a single force- (draw on a scale grid, draw the force to scale , add horizontal and vertical components to grid line , measure them)

Question 29

when a force is applied to an object, it may cause it to stretch compress or bend , how does this happen?

Answer 29

stretching compressing or bending transfers energy, you need more than 1 force acting on the object ,

Question 30

how can you tell if an object has been elastically deformed

Answer 30

if it can go back to its original shape and length after the forc has been removed

Question 31

how is an object inelastically deformed

Answer 31

if it does not return to original shape and length after force has been removed

Question 32

how is work done/ energy transferred to an elastic potential energy store

Answer 32

work is done when a force stretches or compresses an object and causes energy to be transferred to elastic potential energy store of object, if it is elastically deformed, all energy is transferred to object's elastic potential energy store