forces and motion Flashcards
what is the equation for av speed?
speed = d/t
what is speed? what is velocity? how are they different?
speed is the rate of change of distance over time or Distance travelled per unit time, while velocity is the rate of change of displacement over time or Speed in a given direction.
speed is a scalar quantity whereas velocity is a vector quantity with magnitude and direction
what is scalar?
This is because it only contains a magnitude (without a direction)
what is vector?
a vector quantity has magnitude and direction
what is the difference between acceleration, and speed or velocity
acceleration id not the same as them. Acceleration is how quickly velocity is changing
what can a change in velocity be?
change in speed or a change in direction or both
what is the unit for acceleration?
m/s^2
what is the unit for velocity?
m/s
what is the formula for acceleration?
acceleration =change in velocity/ time taken
or
(v-u) / a x t
what does a negative value mean for acceleration
something is slowing down/ decelerating
what is the equation for final velocity?
v^2 = u^2 + 2as
(u=initital velocity)
(s= distance travelled while accelerating)
what does a distance-time graph tell you?
how far something has travelled
what does it mean if a section is flat on a d-t graph?
no movement
what does the gradient on a d-t graph show?
the speed of an object
what do curves, steeper lines, levelling off curve mean in a d-t graph?
curve - acceleration
steep lines- going faster
a curve getting steeper - it is speeding up
levelling off curve- slowing down (decreasing gradient)
what doe the gradient of a velocity time graph mean?
acceleration
what does a flat, steep, uphill/downhill, curve on a v-t graph mean?
flat - represents steady speed
steep - greater acceleration
uphill - acceleration
downhill - deceleration
a curve means changing acceleration e.g., curve getting steeper means greater acceleration and vice versa
what does the area under a v-t graph show?
any part under the graph is equal to the distance travelled in the time interval
what does gravity attract?
all masses
what are the 3 important effects of gravity?
- on the surface of a planet, it makes all things accelerate towards the ground (all with the same acceleration, g, which is about 10m/s^2 on earth)
- it gives everything a weight
- it keeps planets, moons, and satellites, in their orbits. the orbit is a balance between the forward motion of the object and the force of gravity pulling it inwards
what is weight caused by?
the pull of gravity. the wight of an object is often just the force of gravity pulling it towards the centre of the earth
what is special about mass
it is the same anywhere in the universe for any given object
why will an object weigh less on the moon than it does on earth?
because the force of gravity is pulling on it less
what is the unit for weight?
N newtons