motion (P2.1) Flashcards
what do you use light gates for
measuring very short periods of time.
timer
starts and stops when an object interrupts a light beam
ultrasound
high frequency sound waves which is used to measure distance. The device measures the time taken for a pulse to travel there and back. It uses this value, and the speed of the pulse, to work out the distance.
Distance travelled (M) formula
Distance(M)= Speed(M/S) X Time (S)
Average speed (M/S)
Total distance (M) / Total time (S)
SI unit
The SI unit of distance is the metre and the SI unit of time is second.
Converting mph to m/s
- Convert the miles to metres
- Convert hours to seconds
- Divide both of your answers in the formula:
speed= Distance/Time
vector
a quantity that has a magnitude and a force
Scalar
a physical quantity that has magnitude but no direction
Displacement
the moving of something from its place or position.
Velocity
the speed of an object in a particular direction
Acceleration
The change in velocity per second
acceleration formula ( Method 1)
Acceleration= Change in velocity (M/S)/Time(S)
acceleration formula (Method 2)
final velocity-initial velocity/time
Gradient on a graph
The speed an object is moving according to the graph.
Calculating speed from a graph formula
- Draw a right angled triangle under the line
- From the triangle, find the change in distance and change in time
- Use the equation for speed to find the answer.
Calculating velocity from a graph formula
- Draw a right angled triangle under the line
- Find the change in displacement and the change in time from the triangle.
- Use the equation for velocity to find the answer.
What can we deduce from a gradient of a graph
The gradient of any graph with time on the x-axis tells you about the rate of change with time. The rate of change of speed or velocity with time tells you the acceleration.
How do you calculate distance travelled
multiply speed and time
Calculating displacement from graphs
- Identify triangles or rectangles that you can use to calculate the displacement.
- Read the lengths from the graph and use them to calculate the area.
- Calculate the total displacement
Calculating velocity
- Write down the values you know already
- Make the final velocity the subject of the equation
- Calculate the final velocity
Equation of motion
Final velocity-initial velocity= 2X acceleration X distance
Calculating kinetic energy
Kinetic energy= 0.5 X mass X speed
Calculating speed from kinetic energy
- Write what you know and estimate the mass
- Make speed the equation of the equation
- Calculate the speed.
