SP1- Motion Flashcards
What is weight
A force that acts towards the centre of the earth
What do all forces have
Magnitude (size) and a direction
What are forces measured in
Newtons (N)
What are vector quantities
Quantities that have both size and direction
So forces are vectors
How are forces shown in diagrams
Using arrows - longer arrows represent larger forces
What does the weight of a person depend on
The mass
What does mass measure
The amount of matter in something and does not have a direction
What is a scalar quantity
Quantities that do not have a direction
Examples include distance, speed, energy and time
What is displacement
The distance covered in a straight line and has a direction
Displacement is usually less than distance travelled because of bends and Turks in a journey
What does the speed of an object tell you
How far it moves in a certain time
What is velocity
Is speed in a particular direction eg a car may have s velocity of 20m/s northwards
Tell me some examples of vector quantities
Acceleration - a measure of how fast velocity is changing
Momentum - a combination of mass and velocity
What are the common units for speed
M/s or km/h and mph
Tell me the speed distance time triangle
X on top or D (distance) and S (speed) X T(time) on the bottom
What’s the average speed
Worked out from the total distance travelled and time taken
What’s the instantaneous speed
Is the speed at a particular point in a journey
How can you measure speed in a lab
You need to measure a distance and a time, for fast moving objects - use light gates to measure time and will be more
Accurate than a stopwatch
How can a journey be represented
On a distance/time graph
What does a distance/time graph tell us about speed
Horizontal lines means the object is stationary
Straight, sloping lines mean the object is travelling at constant speed
The steeper the line the faster the object is travelling
Have sled is calculated from the GRADIENT Of the line
How do you work out the gradient
The vertical difference between two points on s graph divided by the horizontal difference between the same two points
Then working out the gradient shows the speed
What is a change in velocity
Acceleration - it’s a vector
If a moving object changes its velocity or direction it is accelerating
What is the units of acceleration
M/s^2
So an acceleration of 10m/s^2 means that each second the velocity increases by 10m/s
How do you calculate acceleration
Change in velocity (m/s) divided by time taken in seconds
The triangle is v-u on top and a X t on bottom
V is final velocity
U is the initial velocity
T is the time taken for change in velocity
A is acceleration
What can acceleration mean
Doesn’t always mean getting faster - can also cause an object to get slower - sometimes called a deceleration and acceleration will have a negative value
Tell me the equation to link initial velocity, final velocity and distance travelled
V^2 - U^2 = 2 X a X x
V is final velocity
U is Initial velocity
A is acceleration
X is distance
What does the symbol g means
Gravity
It’s 9.8m/s^2 on earth but rounded to 10 in calculations
How can the changing velocity be shown
By a velocity/time graph
Tell me about velocity/time graphs
A horizontal line means the object is travelling at constant velocity
A sloping line shows that the object is accelerating, the steeper the line - the greater the acceleration
If the line slopes down to the right -
The object is decelerating
You can find the acceleration of an object from the gradient of the line on a velocity/time graph
A negative velocity (line below horizontal axis) shows the object is moving in the opposite direction
How can you calculate the distance travelled from a graph
Multiplying velocity and a time - split the shape into triangles and/ or rectangles and find there areas separately and add them together
