PAG 1.3 Investigating Initial Speed And Stopping Distance Flashcards
What is an interrupt card?
A length of card of a known length. It is attached to a moving object at the height of the light gates, and cites the light beam as it passes through them
How can the initial velocity be calculated from the data recorded by the light-gate?
Light gate records time taken for the interrupt card to pass through. The length of the interrupt card can be divided by the time to obtain the velocity
Where should the light gate be set up in this experiment and what does it record?
Should be positioned at the start of the metre ruler, so that it can measure the initial speed of the block
When pushing the block, why must you release it before it passes through the light gate?
If you are still applying a force as it passes through the light gate, it will cause the block to accelerate,. This will result in an inaccurate initial speed measurement.
Why does the block eventually come to a stop?
The frictional force acting between the block and the surface increases with distance travelled
Describe the energy transfer that takes place in this experiment
Kinetic energy is converted into thermal energy as work is done against friction
Write an energy balance equation for this experiment
1/2mv^2 = Fd
What assumption about friction do we make in this experiment?
Assume that frictional force is constant across the distance travelled. Fair assumption due to relatively low speed
What is the relationship between stopping distance and initial velocity?
v^2 {proportional symbol} d
Predict how the stopping distance of the block will change when it’s initial velocity is doubled
Stopping distance will quadruple
Why is it important that the material of the block and the surface along which it slides is the same throughout the experiment?
So the frictional force doesn’t change throughout the experiment
What graph should be potted with the data obtained from this experiment?
Stopping distance against velocity squared.
The two quantities are directly proportional, this should form a straight line that passes through the origin
Why can’t repeat readings be taken when carrying out this experiment?
It will be difficult to achieve the same exact initial velocity each time
Why might it be advantageous to plot the data points as you carry out the experiment?
You can quickly spot an anomalous result, and take another recording around the same velocity to replace it
