To find out how the height from which a marble is dropped affects the diameter of the crater which it creates on collision with sand.

Sophie Harneiss 11TEH

Physics Coursework

Aim:- To find out how the height from which a marble is dropped affects the diameter of the crater which it creates on collision with sand.

Prediction:- I predict that the higher you drop the marble from, the wider the crater will become. I think this because the higher you drop the ball from, the faster it will be traveling when it collides with the sand. This is because the marble accelerates as it falls; it accelerates because of gravity pulling it towards the earth at 10m/s, however there is another force acting on the marble as it falls, Air Resistance. Air Resistance is an upwards force that changes depending on the surface area of the object that is falling. The smaller the surface area, the less the air resistance, hence the faster it falls. Because the ball accelerates as it falls the higher you drop it from, the more time it has to gain speed and energy before it collides with the sand. Meaning a greater impact on the sand, the more energy the sand has to absorb so the crater is wider. However I think that after a certain height the marble will not cause any bigger crater. I think this because it will eventually reach its Terminal velocity. As the marble speeds up it pushes more air molecules out of the way each second so the air resistance increases, this therefore means that the acceleration decreases. Air Resistance will increase until it is equal to the weight of the marble. When this occurs the forces are equal [balanced] and the acceleration is zero. This is the point when it reaches its terminal velocity and so any height above it will be traveling at the same speed when it hits the sand, therefore the crater will be the same width.

Forces Acting on the Marble:-

There are two forces acting on the marble as it falls. Its weight, and Air resistance. Its weight is caused by gravity which also causes it to accelerate as it falls. Air resistance is caused my the air molecules it is pushing out of the way as it falls.

Diagram 1:-

This Diagram shows the forces which will be acting on the ball as it falls.

Acceleration

Small Gap means

the marble is not

traveling very fast

after 1 second

At the last gap the distance ...