P2 - forces (from textbook)

Question 1

how do you calculate the distance travelled from a velocity - time graph?

Answer 1

the area under the graph

Question 2

define newton’s third law

Answer 2

if object A exerts a force on object B, object B also exerts an equal and opposite force on object A

Question 3

name 3 non-contact forces

Answer 3

electrostatics, magnetism, gravity

Question 4

name 3 contact forces

Answer 4

friction, tension, upthrust

Question 5

define a free body diagram

Answer 5

a diagram that shows the forced acting on a single object

Question 6

define newton’s first law

Answer 6

an object at rest remains at rest, or if in motion, remains in motion at a constant velocity as long as the forces on it are balanced

Question 7

define inertia

Answer 7

a measure of how difficult it is to change the velocity of an object

Question 8

define equilibrium

Answer 8

when the resultant forces is zero

Question 9

name the 3 things a resultant force can do

Answer 9

-change the speed of an object
-change the direction of motion of an object
-change both the speed and direction of motion of an object

Question 10

define the law of conservation of mass

Answer 10

in any collision the momentum before is equal to the momentum afterwards

Question 11

define an elastic collision

Answer 11

when in a collision, no energy is transferred to other stores

Question 12

define an inelastic collision

Answer 12

when in a collision, some energy is transferred to other stores

Question 13

define doing work in science

Answer 13

using forces to transfer energy between stores

Question 14

define a plastic object in science

Answer 14

a material that stretches but doesn’t return to its original shape

Question 15

define an elastic object in science

Answer 15

an object that returns to its original shape when stretched

Question 16

define the limit of proportionality

Answer 16

up to the elastic limit, on a spring’s force/extension graph, force and extension are directly proportional

Question 17

describe what happens when a spring goes beyond the elastic limit

Answer 17

if you remove the force, the spring does not return to its original shape - it becomes permanently deformed

Question 18

define hooke’s law

Answer 18

the extension of a spring is proportional to the forced until you reach the limit of proportionality

Question 19

define the spring constant

Answer 19

the gradient of the linear section of the graph of force against extension

Question 20

describe the relationship between force and extension in an elastic band

Answer 20

non-linear relationship - does not obey hooke’s law

Question 21

what happens when a material deforms?

Answer 21

it stores energy

Question 22

define a gravitational field

Answer 22

a region where a mass experiences an attractive force

Question 23

define weight

Answer 23

the force that acts on an object due to gravity

Question 24

define gravitational potential energy

Answer 24

the energy an object has due to its position in a gravitational field

Question 25

define a moment

Answer 25

a turning effect of a force

Question 26

define the principle of moments

Answer 26

an object is balanced if the anticlockwise moments are equal to the clockwork moments about the pivot

Question 27

describe a lever

Answer 27

a force multiplier that transmits forces by rotating about a pivot

Question 28

define the mechanical advantage

Answer 28

the ratio of the load to the effort