dynamics

Question 1

what does a speedometer in a car record

Answer 1

instantaneous speed

Question 2

what do hand held speed cameras measure

Answer 2

instantaneous

Question 3

what is a scalar quantity

Answer 3

a quantity which only needs a magnitude or size to be described correctly

Question 4

what is a vector quantity

Answer 4

is one which needs a magnitude or a size and a direction to be described correctly

Question 5

name a scalar quantity

Answer 5

distance, time, speed, mass and energy

Question 6

name a vector quantity

Answer 6

displacement, velocity, acceleration, force and momentum

Question 7

define distance

Answer 7

how far you have actually traveled and is measured in metres

Question 8

define displacement

Answer 8

a straight line distance between your start point and your finish point in metres with a direction

Question 9

define speed

Answer 9

distance traveled per second

Question 10

define velocity

Answer 10

displacement travelled per second

Question 11

define acceleration

Answer 11

rate of change of velocity or the change in velocity per second

Question 12

describe the effect of a force

Answer 12

1. change the speed of the object
2. change the direction of travel of an object
3. change the shape of am object

Question 13

what is a balanced force

Answer 13

equal forces acting in opposite directions

Question 14

effects of balanced forces on an object

Answer 14

remain stationary
continue to travel at constant speed

Question 15

explain friction

Answer 15

a force caused by two surfaces rubbing together

it is a force that opposes motion and acts in the opposite direction

Question 16

how to increase friction

Answer 16

• increase the area of rubbing surfaces
• make the rubbing surfaces rougher
• push the rubbing surfaces together more
• increase the speed that the surfaces are rubbed together

Question 17

how to decrease friction

Answer 17

• decrease area of rubbing surfaces
• make rubbing surfaces smoother
• decrease the speed that the surfaces rub together
• lubricate the surfaces
• streamline the object

Question 18

explain streamlining

Answer 18

changing the shape of an object to reduces air/ water resistance or friction

Question 19

state newton’s third law

Answer 19

for every action there is an equal and opposite reaction force

Question 20

what is meant be projectile motion

Answer 20

an object which is being accelerated towards the earth by gravity , it may be falling or it may have a horizontal velocity

Question 21

explain projectile motion

Answer 21

constant horizontal velocity
constant vertical acceleration towards the ground because of gravity

Question 22

explain the orbit of a satellite

Answer 22

after it has launched it has a horizontal velocity but is accelerating vertically towards the earth because of the weight caused by gravity .

if launched with high enough horizontal velocity the trajectory produced will extend beyond the curvature of the earth and the satellite will continue to follow the curved path .

Question 23

what is meant by work

Answer 23

à mesure of the energy used to move and object over a distance using a force

Question 24

what is meant by potential energy

Answer 24

potential energy is the energy stored by an object lifted to a height

Question 25

what is meant by kinetic energy

Answer 25

the energy that any moving object has caused by its mass and velocity