Forces and motion Flashcards
(34 cards)
what are the 9 units used in forces and motion?
- kilogram (kg)
- metre (m)
- metre/seconds (m/s)
- metre/seconds 2 (m/s 2)
- newton (N)
- seconds (s)
- newton/kilograms (N/kg)
- newton metre (Nm)
- kilogram metre/ second (kg m/s)
where is the distance placed on a distance time graph?
on the y axis (usually in metres)
where is the time placed on a distance time graph?
on the x axis (usually in seconds).
what does it mean when the line in the distance time graph is flat?
it means the object is stationary.
what does the gradient of the line (change in y/ change in x) mean?
speed
what is the formula you use to calculate the average speed?
speed (m/s) = distance travelled (m)/ time taken (s)
Practical: how to investigating the motion of everyday objects such as toy cars or tennis balls?
(there are 8 points)
- You need a stop watch and metre rule.
- mark the start and end positions (to know the difference).
- use a metre ruler to measure the distance.
- put the toy car on the starting point and release it.
- start the timer and stop it only when the car gets to the end point.
- write down how long it took.
- finally calculate the average speed by using the formula average speed = distance travelled/ time taken.
- repeat experiment more than once.
what is the formula for acceleration?
acceleration = final velocity - starting velocity/ elapsed time
where does velocity go on a velocity time graph?
on the y axis (usually in m/s)
where does time go on a velocity time graph?
on the x axis (usually in s)
what does it mean when the line is flat on a velocity time graph?
it means the object is moving at a constant velocity.
what is the gradient on a velocity time graph?
it is the acceleration.
how do you calculate the distanced travelled on a velocity time graph?
you calculate the area under the line
what formula do you use to calculate acceleration from the gradient of a velocity time graph?
gradient = acceleration = change in velocity/ time
how to calculate the area under the graph?
It can be calculated as rectangles and triangles.
what is the formula that calculates the relationship between final speed, initial speed acceleration and distanced moved?
(final speed) 2 = (initial speed) 2 + (2 x acceleration x distanced moved)
v2 = u2 + (2 x a x s)
key: v = final speed u = initial speed a = acceleration s = distanced moved (word2 = word squared)
forces can act on a body to change what 3 things ?
- velocity
- speed
- direction
can forces act on the shape of a body?
yes, it can stretch it, squish it and twist it.
what are the 9 different types of force?
- gravitational
- weight
- friction
- electrostatic
- air resistance (drag)
- tension (force in a spring)
- up thrust
- lift
- thrust
is force a vector?
yes, it has a direction, a push or pull, up, down, left or right.
how to calculate a resultant force with lines that go to the same side?
you add them together.
e.g there are 2 arrows in the same side (right) of the car.
one is 30N the other is 60N.
the resulted force will be = 90N to the right
how to calculate a resultant force with lines going the opposite side side?
you subtract the forces.
e.g there are town arrows, one in the right side and one in the left side of the car
the left side is 10N and the right side is 30N
you subtract them together (subtract the smaller force from the bigger force), meaning that the resultant force is = 20N to the right (because the right side has a bigger force)
how is friction caused?
it is caused by rubbing surfaces.
how does friction act?
it acts the opposite direction to motion.
