# speedVel

MOTION

1. Linear motion

Units of mass, length and time – definition of units not required.

Unit of mass is the kilogram (kg)

6.02214179×1023 atoms of 12C.

Unit of length is the metre (m)

Unit of is time is the second (s)

Displacement, velocity, acceleration: definitions and units.

The Difference between Distance and Displacement here http://physics.info/displacement/

The Difference between speed and Velocity here http://physics.info/velocity/

The Physics of changing speed (velocity) http://physics.info/acceleration/

Measurement of velocity and acceleration, using any suitable apparatus.

Use of distance-time, velocity-time graphs.

http://vnatsci.ltu.edu/s_schneider/physlets/main/kinvec0.shtml

http://vnatsci.ltu.edu/s_schneider/physlets/main/kinem01.shtml

Sports, e.g. athletics.

Usain Bolt, 10.438 ms-1 37.578 kmph Telemetry ??

The explosive velocity of TNT is 6900 m/s

Appropriate calculations.

if the radius of the earth is 6367.3 km how fast does a house travel ?

if the radius of the earths orbit around the sun is 1.4959 x 1011m how fast does the earth travel through space, m/s

Constant Velocity

If something does not accelerate then it moves with a constant velocity

If it passes through a set of timer 'gates' then the time taken for both passes will be the same, then we are assured that the velocity is constant.

We could then change the set up so one gate acts as the start timer and the other gate acts as the end timer, get the distance between them and calculate the velocity,

here this guy does it well

http://www.animations.physics.unsw.edu.au/jw/electricmotors.html#mandg

Set up air track so the velocity is constant.

Constant velocity mean no acceleration,

therefore the gate time at the top must equal the gate time at the bottom.

there will be a small amount of air resistance slowing the glider down

this negative acceleration causing the slowing down can be overcome by a slight slope on the track, thus providing a small amount of force to counter act the air resistance.

When you are happy with the readings are constant change the plugs on the timer so both are connected to a single panel. Change the switch so it is set to the start/stop setting.

Push the glider down the ramp 5 times. For each run record the time it takes to go between the two gates. Measure the distance as accuratly as is possible.

Calculate the velocity as distance ÷ time for 5 different runs.

Distance(m) Time(s) Velocity (m/s)

An applet to do this using a trolley see the following link

http://www.mathsphysics.com/Physics/VelocityandAcc.htm

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