Motion Flashcards
Define time
Symbol for time
Si unit for time
The ongoing sequence of events taking place
t
seconds
Define displacement
Symbol for displacement
Si unit for displacement
The shortest distance between the initial position and the final position
s
Metres
Define distance
Symbol for distance
Si unit for distance
The numerical measurement of space between two objects
s or d
Metres
Define speed
Symbol for speed
Si unit for speed
The rate at which distance is covered in a given period of time
v
m/s or ms^-1
Define velocity
Symbol for velocity
Si unit for velocity
A measurement of an objects motion and the direction of its motion.
v
m/s or ms^-1
Define acceleration
Symbol for acceleration
Si unit for acceleration
Formula
The rate at which velocity changes over time, due to either change in speed or change in direction
a
m/s/s or m/s^2 or ms^-2
Change in velocity/change in time
speed, distance, time triangle
d
v. t
velocity, displacement, time triangle
s
v. t
Define force
Symbol for force
Si unit for force
Measured with
A push, pull or twist that changes the motion of an object
F
Newtons
Spring Balance
Define mass
Symbol for mass
Si unit for mass
Formula
The amount of matter in an object
m
kilograms
weight /gravity
Newton’s second law of motion
A force applied to an object will accelerate it proportional to the force, and inversely proportional to its mass
F=ma
Newton’s first law of motion
An object at rest will remain at rest, unless an unbalanced force acts on it, and an object in motion will remain in motion unless an unbalanced force acts on it.
Newton’s third law of motion
For every action (force) there is an equal and opposite reaction (force)
Define weight Symbol for weight Si unit for weight Measured with Formula
The force exerted upon an object due to gravity W Newtons Spring Balance mass x gravity
Define motion
Any physical movement or change in position or place relative to a reference point
Define inertia
The tendency of an object at rest to remain at rest, and of an object in motion to remain in motion
Define gravity
The force of attraction between all masses in the universe
Define deceleration
The rate at which velocity decreases over time
Define vector quantity & scalar measurement
The measurement is expressed as a size (magnitude)and a direction
A quantity that only has size and no direction.
Define average speed
Symbol
A measure of how fast something moves overall
s or v
What does average velocity describe
How fast the displacement is changing
+ or - depending on direction
Define instantaneous speed
Your speed at a particular instant.
How is acceleration determined as + or -
If the speed is increasing, the acceleration is positive. If the speed is decreasing, the acceleration is negative and is called deceleration.
Describe distance time graphs
A distance time graph shows how an object’s motion changes over a period of time.
Time is always placed on the horizontal or x-axis and distance is always plotted on the vertical or y-axis
Describe speed time graphs
A speed-time graph shows how an object’s speed changes over time. As in distance -time graph, time is placed on the horizontal or x-axis and speed or velocity is placed on the vertical or y-axis.
An object’s speed may :
be constant shown by a flat horizontal line.
increase (acceleration) shown by straight line sloping upward on the s-t graph.
decrease (deceleration), shown by a straight line sloping downwards on a s-t graph.
How to calculate distance in s-t graphs
The total distance traveled in a journey is represented by the AREA under the v-t graph. The way to calculate this is to break your graph up into “shapes” and find the area of each shape (just like you would do in Maths)
so AREA = DISTANCE TRAVELLED
Analysing ticker timers
The distance between successive dots on a ticker tape depends on the velocity of the tape.
If the tape moves quickly, the dots are far apart.
If the tape moves slowly, the dots are close to each other
How to calculate average speed in ticker timers?
The average speed between each pair of dots can be determined by dividing the distance between the dots by the time interval
What can forces do?
move a stationary object
speed up (accelerate) or slow down (decelerate) a moving object.
- stop a moving object
- change the direction of a moving object and
- change the shape of an object
How to draw forces?
Scientists draw forces using arrows.Arrows allow you to show both the direction and size of the force. The direction of the arrow shows the direction of the force. Long arrows show big forces and short arrows indicate small forces.
Define balanced and unbalanced forces
When two forces are equal in magnitude but opposite in direction acting on the same body.
When two forces are unequal in magnitude but opposite in direction acting on the same body.
What did Newton’s laws of motions do?
Describes how things move, accelerate and interact with each other.
Weight mass gravity triangle
W
m g
Example of newton’s laws of motion
Seat belts stop you tumbling around inside the car if there is a collision. Upon sensing a collision the seat belts lock in place. When the car crashes, there is no unbalanced force acting on the person, so they continue forward (Newton’s First Law). The person moves against the seat belt, exerting a force on it. The seat belt then exerts a force back on the person (Newton’s Third Law). This causes a controlled deceleration of the person.
