Acceleration

• What is acceleration?

  Tell us the change in velocity over a given time.
• What is the equation for acceleration?

  acceleration (m/s / s) = final velocity (m/s) - initial velocity (m/s) / time (s)
• What is it called when an object decreases in speed?

  deceleration
• What does the gradient of a velocity time graph tell us?

  The acceleration of the object
• What does a horizontal line mean in a velocity-time graph?

  Means the object is travelling at a constant velocity
• what does an upward slope mean on a velocity-time graph?

  The object is accelerating
• What does a downward slope mean on a velocity-time graph?

  The object is decelerating
• What does the total area under the velocity-time graph tell us?

  Tells us the distance travelled in a specific direction (displacement)
• How do you calculate the total area under the velocity-time graph when the acceleration and deceleration are not constant?

  You need to count the number of whole squares under the graph and then estimate the total of the parts of not whole squares.

  There are 15 whole squares and the total parts of the not whole squares adds up to roughly 5, so the total no. of squares under the graph is 20, each square has an area of 250. So 20 x 250 gives us a total distance or displacement of 5000m

  
• If an object is accelerating at a constant rate, what equation do you use?

  V ^2 (final velocity m/s ) - U ^2 (initial velocity m/s) =

  2as( a= acceleration m / s / s )(s= distance m)
• What is the initial acceleration of an object which falls towards the surface of the Earth?

  9.8 m / s / s
• What happens as a skydiver falls?

  Initially they accelerate due to the force of gravity acting on the object, they then experience an upward force of friction with the air particles (air resistance), after time, the force of air resistance balances the force due to gravity. At this point, the object stops accelerating and moves at a constant velocity, this is called the 'terminal velocity' . This applies to any object falling through a fluid, in this case the fluid is air.
• what does terminal velocity depend on?

  The object - some experience a greater force of friction due to their shape so they will have a lower terminal velocity.