physics term 3 Flashcards
formula for area of triangle
1/2 x base x height
important to finding areas under a graph
formula for volume
multiply length, width and height
formula for volume of a cylinder
pi x r^2 x h
r = radius and h = heigh
formula for density
density = mass/volume
explain another method for calculating volume that involves water and state the reason why we would use this
fill a measuring cylinder with water. Record the measurement. add your object in to the measuring cylinder. Record the new measurement. Subtract the two measurements. You now have the volume of the object.
reason: measuring the volume of an irregular object
formula for acceleration
change in velocity/time taken
a student is measuring the density of a liquid. He places a measuring cylinder on a balance and records its mass. He then pours the liquid into the cylinder and records the new reading on the balance. He also records the volume of the liquid
mass of empty cylinder = 147 g
mass of cylinder + liquid = 203 g
volume of liquid = 59 cm^3
using the results shown, calculate the density of the liquid
remember. density = mass / volume
to find the mass we subtract the mass of the empty cylinder by the mass of cylinder + liquid
= 203 g - 147 g = 56 g
since the volume of the liquid is already given to us (59 cm^3) we just need to plug everything in
d = m/v —> density = 56 g / 59 cm^3 = 0.94 g/cm^3
the inside of a sports hall measures 80m long by 40m wide by 15m high. the air in it has a density of 1.3kg/m^3 when it is cool.
a) calculate the volume of air in the sports hall
b) calculate the mass of the air. state the equation you are using
a) 80mx40mx15m = 48000 m^3
b) d = m/v —–> m = d x v —-> m = 1.3kg/m^3 x 48000 = 62,400 kg/m^3
explanation: we already know the formula for density. if we rearrange it we get the formula for mass. The density was already given to us. We already calculated the volume (48000 m^3). so all that’s left to do is plug everything in.
equation for calculating average speed
= total distance / total time
differentiate scalar and vector quantities and provide examples of the 2.
scalar quantity has magnitude only and NO direction.
for example: speed, distance
vector quantity has magnitude AND direction.
for example: acceleration, velocity and weight.
scientific terms for speed up and slow down
accelerate and decelerate
an object may be acted on by several forces. What name is give to the single force that has the same effect as these forces
resultant forces
state the equation that links the following quantities:
force, mass and acceleration
= newtons second law of motion which is:
F= ma (force is equal to mass x acceleration)
state the unit for mass and whether it is scalar or vector
unit: kg
it’s scalar
state the unit for acceleration and whether it is scalar or vector
unit: m/s^2
vector
state the unit for force and whether it is scalar or vector
unit: N (newtons)
it’s vector
a tennis ball is falling.
if the two forces (weight and air resistance) are equal but are in opposite directions, then what is the resultant force acting on the ball?
explain why the ball falls at a steady speed and what is the name given to the steady speed?
resultant force = 0
the ball falls at a steady speed because the forces are balanced.
name of the steady speed = terminal velocity
an astronaut with a mass of 80 kg goes to the moon. What will his weight be on earth? what will happen to his mass on the moon? what will happen to his weight.
weight = 80 kg x 10 m/s^2 = 800N
(because weight is the gravitational pull someone has. the formula for weight is the same as formula for force = f = mass x acceleration. and on earth that’s 10 m/s^2)
his mass will be the same
His weight will be less
A train of mass 800 000 kg is slowing down. what acceleration is produced if the braking force is 1 400 000
acceleration = force/mass —–> 1 400 000 / 800 000 = 1.75 m/s^2
electrical energy may be obtained from nuclear fission
in which order is the energy transferred in this process
a. nuclear fuel –> generator —> reactor and boiler —> turbines
b. nuclear fuel –> generator —> turbines —> reactor and boiler
c. nuclear fuel –> reactor and boiler —> turbines —> generator
d. nuclear fuel –> reactor and boiler —> generator —> turbines
C.
Which energy is stored in a cell and how is this energy usually transferred ?
type: chemical
transferred by: electric current
niki wants to measure the volume of a highlighter
which apparatuses would not be useful
A. beaker B. displacement can C. Pestle and Mortar D. measuring cylinder E. Balance
C. and E
name a conductor and an insulator
conductor: iron
insulator: plastic
two magnets are side by side
the first one’s north is on the left and the south is on the right
the second one’s north is also on the left and the south is on the right
are the magnets attracting or repelling each other ?
attracting because opposites attract.
what is the energy conversion of hydroelectricity
Gravitational potential energy to mechanical energy to electricity
Ten identical lengths of wire are laid closely side by side. Their combined width and thickness is measured and found to be 14.2 mm
calculate:
A) average thickness of one rod
a) 1.42
explanation: average thickness = total thickness divided by number of rods (in this case we’re measuring rods)
thickness is said to be 14.2mm
number of rods = 10
14.2mm/10 = 1.42mm
Ten identical lengths of wire are laid closely side by side. Their combined width and thickness is measured and found to be 14.2 mm
calculate:
b) the radius of a single wire
r = 0.71
the combined width is the sum of the diameters of the ten rods, thus: 14.2 / 10 = 1.42 (this is the diameter)
diameter = 2x radius
so all we have to do is divide the diameter by 2 to find the radius
1.42 / 2 = 0.71
Ten identical lengths of wire are laid closely side by side. Their combined width and thickness is measured and found to be 14.2 mm
calculate:
c) the volume in mm of a single wire if its length is 10.0 cm
158.39mm^3
explanation/step by step guide:
1. change the length from cm to mm
remember! 1 cm = 10mm
10.0cm = 100mm
remember! volume = pi x radius^2 x height
v= pi (3.14) x 0.71 (as mentioned in previous card) x 100 (the mm) = 158.39mm^3
name the 3 types of magnets
permanent magnet
temporary magnet
electromagnet
fill in the blanks
Permanent magnets emit a ________ field without the need for any _______ source of magnetism or __________ power.
permanent magnets emit a MAGNETIC field without the need for any EXTERNAL source of magnetism or ELECTRICAL power
What are the differences between electromagnets and permanent magnets ?
Permanent magnets are permanently magnetized while electromagnets are temporarily magnetized.
You can change the strength of an electromagnet by controlling the electric current and you can even switch if off or on whereas permanent magnets magnetic field is generated by the internal structure of the material itself.
state one thing you can do to ensure that an experiment is accurate
- repeating the experiment multiple times
what is the formula for power?
power = work / elapsed time
formula for efficiency
efficiency = output / input
how do you magnetize iron ?
get the north pole of a magnet.
stroke the iron with the north pole of the magnet from the middle to the end in the same direction several times.
what is static electricity?
its the charge that builds up on the surface of an object
what is induction used for?
induction is used to induce a charge on an uncharged object without contact
what is conduction ?
Conduction is the process by which heat energy is transmitted through collisions between atoms or molecules
what is convection ?
movement in a gas or liquid in which the warmer (less dense) parts move up and the cooler parts (more dense) move down which results in transfer of heat.
what is radiation ?
radiation is the emission or transmission of energy in the form of waves or particles through space or through a material medium.
state by which process thermal energy is spread through a fluid
convection
what is an absorber ? give an example
it is any object that can absorb thermal radiation
example: a matte black surface
