general physics Flashcards
4 vector
force, weight, velocity, acceleration, momentum,
electric field strength and gravitational field
strength
4 scalar
distance, speed, time, mass, energy and
temperature
Define mass
measure of the quantity
of matter in an object at rest relative to the
observer
define weight
gravitational force on an
object that has mass
gravity [3]
3) g =
W / m
1) force per
unit mass
2) equivalent to the
acceleration of free fall
How is weight (mass) compared
by using a balance
Define density
mass per unit volume
ρ = m / V
Determine whether an object floats based on
density data
Object will float if its density is less than the density of the solution it is in
is weight a force
true
Si units for gravitational field strength
(N/kg)
SI unit for weight
N
SI unit for mass
kg
SI unit for density
kg/m^3
It is incorrect to describe the circular motion as having constant velocity
The direction of motion is changing OR constant velocity must be in a straight line
A force is required to maintain circular motion because [2]
A resultant force is needed for an object to change direction OR without a resultant force the object would continue moving at a constant velocity in a straight line; [1 mark]
The car is moving in a circle so it is changing direction, so the velocity is changing / the car is accelerating; [1 mark]
For objects in circular motion, the force acts
Towards the centre of the circle OR at right angles to the motion
The name of the inward acting force for the car in circular motion on the track
Friction; [1 mark]
[Total: 1 mark]
Remember that centripetal force is not a force in its own right but is the force that keeps an object moving in a circle.
If there was no friction between the car tyres and the track, the car would not be able to move in a circle. The friction acts towards the centre of it and is the centripetal force in this situation.
How would you find the speed of the train at time t = 100 s on a distance time graph [2]
1) Draw tangent
2) Calculate Change in distance / change in time (gradient)
it needs to be on exactly 100s so we do it precisely
What happens to the acceleration of a straight line on a distance time graph?
It becomes 0
Because acceleration is only produced when velocity changes
Define deceleration
Negative acceleration
The initial acceleration of the train is 0.75 m/s .
Calculate there sultant force that acts on thet rain at this time. The train is 5.6 × 10^5 kg
F=ma
F= 5.6x10^5 * 0.75
= 4.2 × 10^5 N
Define acceleration
Rate of change of velocity; [1 mark]
OR
fraction numerator C h a n g e space o f space v e l o c i t y over denominator T i m e end fraction [1 mark]
Centre of gravity define
Place where all the weight acts
2 methods of generating electrical power not from the sun
1) Geothermal
2) Nuclear
