Motion, Forces and Energy Flashcards
How can you find a length?
using a ruler or tape measure
How can you find a volume?
using a measuring cylinder
How can you measure a variety of time intervals?
using clocks and digital timers
centi=
divide by 100
milli=
divide by 1000
kilo=
times by 1000
mega=
times by 1 000 000
giga=
times by 1 000 000 000
What is a scalar quantity?
a quantity that has only magnitude
What is a vector quantity?
a quantity that has both magnitude and direction
What are some scalar quantities?
- distance
- speed
- time
- mass
- energy
- temperature
What are some vector quantities?
- force
- weight
- velocity
- acceleration
- momentum
- electric field strength
- gravitational field strength
What is speed?
distance travelled per unit time
speed formula
v = s/t
What is velocity?
speed in a given direction
formula for average speed
total distance travelled/total time taken
What shows CONSTANT SPEED on a DISTANCE-TIME graph?
a straight, sloping line
What shows A HIGHER CONSTANT SPEED on a DISTANCE-TIME graph?
a straight, sloping line of higher gradient
What shows STATIONARY object on a DISTANCE-TIME graph?
flat/horizontal line
On a distance-time graph, a flat horizontal line means?
the object is stationary
On a distance-time graph, a straight sloping line means?
constant speed
On a distance-time graph, a straight sloping line with a higher gradient means?
higher constant speed
How can you calculate speed from a distance–time graph?
find the gradient
For a speed–time graph, a flat horizontal line at zero speed means?
stationary
When is an object stationary in a speed-time graph?
flat horizontal line at zero speed
For a speed–time graph, a flat horizontal line (>0) means?
constant speed
When is an object in constant speed in a speed-time graph?
a flat horizontal line above zero speed
For a speed–time graph, an upward sloping line means?
accelerating; the steeper the gradient, the higher the acceleration
When is an object accelerating in a speed-time graph?
an upward sloping line
For a speed–time graph, a downward sloping line means?
deceleration
When is an object decelerating in a speed-time graph?
downward sloping line
How can you measure distance in a speed-time graph?
Calculate the area under the speed–time graph
What is the acceleration of free fall g for an object near to the Earth’s surface?
approximately constant and is approximately 9.8 m/s2
What is acceleration?
change in velocity per unit time
formula acceleration
a = ∆v / ∆t
What indicates constant acceleration in a speed-time graph?
a straight line
What indicates changing acceleration in a speed-time graph?
a curved line
How can we calculate acceleration from a speed-time graph?
finding the gradient
What is a deceleration?
a negative acceleration
Describe the motion of objects falling in a uniform gravitational field without resistance.
after dropping, immediately accelerates because gravity pulls the ball downwards
all objects fall with same rate of acceleration, no matter their mass
Describe the motion of objects falling in a uniform gravitational field with resistance.
gravity produces a force pulling downwards, but air resistance pushes back upwards. The more air resistance, the smaller the acceleration.
Eventually, downwards force of gravity is balanced by air resistance, preventing any more acceleration, reaching terminal velocity.
What is terminal velocity?
The top speed reached by any object experiencing air resistance or a similar resistance force.
What is mass?
a measure of the quantity of matter in an object at rest relative to the observer
What is weight?
a gravitational force on an object that has mass
What is gravitational field strength?
force per unit mass, equal to the acceleration of free fall
formula for gravitational field strength
g = W/m
formula for weight
w = mg
How can weights and masses be compared?
using a balance
What is a balance used for?
to compare masses and weights
What is weight, in extended terms?
the effect of a gravitational field on a mass
What is density?
mass per unit volume
Formula for density
p = m/v
How can you determine a liquid’s density?
- place empty measuring cylinder balance and tare the balance
- pour liquid into the measuring cylinder
- record mass from balance and volume from the measuring cylinder
How can you determine a regular solid’s density?
measure mass by balance and volume of shape
How can you determine an irregular solid’s density?
- fill measuring cylinder around half-full with water
- find mass of the object
- measure initial volume of liquid
- place the object into the water. Take a new reading.
- repeat with different starting amounts of water to find its volume
1 cmˆ3 of water =
1ml or 1g
1000 cmˆ3 of water =
1 litre or 1kg
1 mˆ3 of water =
1000 litres or 1000kg
How can we determine whether an object floats?
seeing if its density is bigger than or smaller than water’s (1 g/cmˆ3)
What may forces produce?
changes in the size and shape of an object
If no forces act on it, what occurs to an object?
either remains at rest or continues in a straight line at constant speed
What may a resultant force change?
the velocity of an object by changing its direction of motion or its speed