Section 1 - Motion, Forces and Conservation of Energy Flashcards
What are vectors?
Quantities with both magnitude and direction.
What are scalars?
Quantities with magnitude only.
What are some examples of vector quantities?
Force, velocity, displacement, weight, acceleration and momentum.
What are some examples of scalar quantities?
Speed, distance, mass, energy, temperature and time.
What is a distance, in physics, defined as?
How far an object has moved.
What is displacement, in physics, defined as?
The distance and direction in a straight line from an object’s starting point to it’s finishing point.
What is speed, in physics, defined as?
Speed is a measure of how fast something is going.
What is velocity, in physics, defined as?
How fast something is going and in what direction.
Describe the formula relating (average) speed & time.
d=s×t
d = distance s = (average) speed t = time
What is acceleration, in physics, defined as?
The change in velocity over a certain amount of time.
What is uniform acceleration, in physics, defined as?
Speeding up (or slowing down) at a constant rate.
Describe the formula relating acceleration, time and change in velocity.
a=(v-u)/t
a = acceleration v = final velocity u = initial velocity t = time
Describe the formula for constant acceleration.
v²-u²=2×a×x
v = final velocity u = initial velocity a = acceleration x = distance
Which graph shows how far something has traveled?
Distance/Time graphs.
Which graph can have both positive and negative gradients?
Velocity/Time graphs.
In a distance/time graph, how can speed be worked out?
Speed = gradient = change in y / change in x
In a velocity/time graph, how is distance worked out?
By calculating the area under the graph.
What is Isaac Newton’s first law?
Every object persists in its state of rest or uniform motion in a straight line unless it is compelled to change that state by forces impressed on it.
Or a still object will not move unless forced to, and a moving object will not stop or change direction unless forced to.
Describe the equation relating resultant force and acceleration.
F=m×a
F = resultant force m = mass a = acceleration
List some safety features used in cars.
Seat belts, air bags and crumple zones.
What is mass, in physics, defined as?
The amount of ‘stuff’ in an object.
What is weight, in physics, defined as?
Mass with gravity.
Describe the equation for weight.
W=m×g
W = weight m = mass g = gravitational field strength
What is Isaac Newton’s second law?
Force is equal to the change in momentum per change in time. For a constant mass, force equals mass times acceleration.
What is inertia?
Inertia is the tendency for motion to remain unchanged.
What is Isaac Newton’s third law?
For every action, there is an equal and opposite reaction.
What is momentum, in physics, defined as?
The property that all moving objects have.
Describe the equation for momentum.
p=m×v
p = momentum m = mass v = velocity
How, in a closed system, is momentum affected after an event. What is it called.
It isn’t, momentum before an event is equal to the momentum after the event. This is known as conservation of momentum.
Describe the equation relating force and change in momentum.
F=(mv-mu)/t
F = force m = mass v = final velocity u = initial velocity t = time
List the types of Energy Store.
Kinetic Thermal Chemical Gravitational Potential Elastic Potential Electrostatic Magnetic Nuclear
Describe the equation for working out the work done by a vehicle’s brakes.
1/2×m×v²=F×d
m = vehicle's mass v = velocity F = braking force d = braking distance
Describe the equation for kinetic energy.
KE=1/2×m×v²
KE = Kinetic Energy m = mass v = velocity
What is Kinetic Energy?
Energy which a body possesses by virtue of being in motion.
Describe the equation for a change in Gravitational Potential Energy.
ΔGPE=m×g×Δh
ΔGPE = change in Gravitational Potential Energy m = mass g = gravitational field strength Δh = change in height
What is Gravitational Potential Energy?
Gravitational Potential Energy is energy an object possesses because of its position in a gravitational field.
What is Conservation of Energy?
The fact that energy can neither be created or destroyed.
List the four main methods of energy transfer.
Mechanically
Electrically
By heating
By Radiation
How is energy made useful?
By transferring it into a useful store.
Describe the equation for efficiency.
Ef=(Eu÷Et)×100
Ef = Efficiency
Eu = Useful energy
Et= Total energy
How can efficiency be increased?
By removing unwanted energy transfers.
How can unwanted energy transfers such as friction and heating be removed?
Lubrication reduces energy transfer by friction. Insulation reduces energy transfer by heating.
List the types of energy sources. Are they renewable or non-renewable? polluting or non-polluting?
Fossil fuels, non-renewable, polluting Nuclear, non-renewable, polluting Bio-fuels, renewable, polluting Wind, renewable, non-polluting The sun, renewable, non-polluting Hydro-electric, renewable, non-polluting Tides, renewable, non-polluting
What are current trends in Energy Resource use?
Currently we depend on fossil fuels, followed closely by nuclear fuels. However, we are slowly drifting towards renewable, non-polluting fuels like wind and solar.
What percentage of the total energy produced in the UK produced using renewable resources?
15%
What is limiting the current efforts to shift to renewable energy sources?
Cost, reliability, aesthetics, research, personal changes.
