Gravity and Motion Y9

Question 1

What is the standard unit of speed?

Answer 1

metres per second, m/s

Question 2

What is the equation of speed?

Answer 2

speed = distance / time

Question 3

What is the method to calculate speed, acceleration, weight and velocity?

Answer 3

DAFNE:
D - list your data
A - adjust the units
F - write the formula
N - add the number values into the formula
E - answer equals

Question 4

Define ‘speed’

Answer 4

a scalar: the distance travelled per unit of time/ how fast an object travels

Question 5

Define a ‘scalar’ quantity

Answer 5

quantity with magnitude (size) only, eg. distance, speed, mass, energy, time

Question 6

Define a ‘vector’ quantity

Answer 6

quantity with a magnitude (size) and direction, eg. displacement, velocity, acceleration, momentum, force

Question 7

Define ‘distance’

Answer 7

a scalar: how far an object travels

Question 8

Define ‘displacement’

Answer 8

a vector: how far an object travels in a particular direction

Question 9

Define ‘velocity’

Answer 9

a vector: how fast an object travels in a particular direction

Question 10

What is the equation for velocity?

Answer 10

velocity = displacement / time

Question 11

Define ‘acceleration’

Answer 11

a vector: the change in velocity per unit of time

Question 12

What is the equation for acceleration?

Answer 12

acceleration = change in velocity / time

Question 13

What are the units of acceleration?

Answer 13

metres per second per second, m/s²

Question 14

Define ‘friction’

Answer 14

the resistance that an object encounters when moving over another

Question 15

Define ‘drag’

Answer 15

the friction force that occurs when an object moves through a medium (liquid or gas)
eg. air resistance or water resistance

Question 16

Define ‘tension’

Answer 16

felt by ropes and wires that are being hung or pulled

Question 17

Define ‘normal contact force’

Answer 17

force that acts on an object touching another+ acts at 90 degrees to the surface

Question 18

Define ‘upthrust’

Answer 18

upward force on an object that is floating in a liquid

Question 19

Define ‘magnetism’

Answer 19

force that a magnet puts on a magnetic material (including other magnets+metals)

Question 20

Define ‘gravitational force’

Answer 20

an attractive force between two objects with mass, eg. the pull of the earth on the moon, measured in Newtons

Question 21

Define ‘weight’

Answer 21

the force on a mass due to gravity, eg. the force a person exerts on the ground due to gravity, measured in Newtons

Question 22

Define ‘electrostatic force’

Answer 22

force caused by electrically charged objects

Question 23

Define a ‘zero resultant force’

Answer 23

the direction and velocity of an object will stay the same as the forces are balanced

Question 24

Define a ‘non-zero resultant force’

Answer 24

the shape, size, direction or speed of an object will change as the forces on the object are not balanced

Question 25

How do you calculate the resultant force?

Answer 25

1. if the forces on an object are parallel & in the same direction, it is found by adding them together
   eg. 40N forwards + 10N forwards = 50N forwards
2. if the forces on an object are parallel & in the opposite direction, it is found by subtracting them
   eg. 60N forwards + 15N backwards = 45N forwards
   always subtract the backwards force from the forwards force
3. if the forces on an object are perpendicular:
   a. draw lines parallel to the two forces to create a parallelogram
   b. draw a line through the middle, connecting the point where the two forces meet to the point you just created
   c. the angle of the line is the angle of the resultant force & the length represents the size of the resultant force

Question 26

What are the rules for distance-time graphs?

Answer 26

flat/horizontal line - object is stationary
straight diagonal line - object has a constant speed
curved line - object has a changing speed (steeper=faster, shallower=slower)

Question 27

What are the rules for velocity-time graphs?

Answer 27

flat/horizontal line - steady speed/constant velocity, or stationary if steady speed is 0)
straight diagonal line - object has a constant acceleration
curved line - object has a changing acceleration

Question 28

What is the equation for finding the gradient of a line?

Answer 28

gradient = change in y / change in x

gradient = rise / run

units for gradient - m/s²

Question 29

Define ‘terminal velocity’

Answer 29

the maximum speed an object can accelerate to, due to the drag and weight forces of an object becoming balanced

Question 30

Define ‘mass’

Answer 30

the amount of material present in an object, measured in kg
the mass of an object does not change when moved to a different place in the universe

Question 31

What is the equation for weight?

Answer 31

weight = mass x gravitational field strength

Question 32

Define ‘satellites’

Answer 32

an object that orbits something else in an elliptical/oval shape, due to the pull of gravity from other objects in space
eg. earth orbits the sun, the moon orbits earth

natural satellite - was put there by nature
artificial satellite - was put there by humans

Question 33

State 2 artificial satellite orbits

Answer 33

Low Polar Orbits: satellites that pass over the poles in 90mins for each orbit. the earth spins beneath the satellite as it moves so it can scan the surface of the earth
uses - monitoring weather, observing the surface, military uses/spying

Geostationary Satellites: satellites in orbit over the equator in 24hrs for each orbit. they stay in a fixed position over the earth’s surface and monitor a particular area
uses - communications/satellite tv, global positioning/GPS Sat Navs