Factors Affecting the Speed of a Car after Freewheeling down a Slope

Background Knowledge

Sir Isaac Newton formulated three Laws relating to the motion of objects.

A moving object covers a particular distance in a particular time. This is called the Speed of the object and is expressed as meters/second i.e. the distance covered in meters in one second. It is a Scalar quantity as it only has magnitude. If however the same speed is expressed with the object moving in a particular direction e.g. due north, it will be called the Velocity of the object. It again is expressed as meters/second but having both magnitude and direction it is a Vector quantity.

Newton described that an object that is stationary will stay stationary until a force is applied to it and an object that is in motion will stay in motion in a straight line until it is acted upon by a force. This is Newton’s First Law of Motion.

Average Velocity = Displacement taken place (m)

(m/s)                        Time taken (s)

Force is a push or a pull, which can make an object start moving when it is stationary, or change its shape or its direction of motion. It is measured in Newton (N).

When an external force acts upon a moving object it changes its velocity. The rate at which this velocity is changed is called acceleration  (if the velocity is increased) or deceleration (if the velocity is decreased by an opposing force). This is the Second Law of Motion. And acceleration is expressed in m/s2.

Acceleration = Change in Velocity (m/s)

(m/s2 )                   Time taken (s)

It is the property of matter that it opposes any change in an object’s fixed position. This is called Inertia.

The results of this investigation are displayed below.

After looking at the results I decided to keep the runway at 50 cm as this gave a better speed-readings. I felt this height would be preferable for my final experiment as a small error in higher readings is less likely to show effect and than those with low readings. It would also allow me to chart the graph better with high readings.

MASS OF THE TROLLEY

1. The trolley by itself has a mass of 1kg so this was tested first as the lighter reading.
2. The ticker timer and tape were set up as in the previous investigation.
3. The trolley was released at the top of the ramp and stopped when it had passed 1 metre on the flat ramp.
4. The tape was measured as before and the number of dots recorded as in the first section of the experiment.
5. Ten 100g masses were cellotaped in pairs to the top of the trolley.

As a further experiment, I could see how other factors like surface of the runway; type of trolley, mass of trolley and contact area would affect the speed of the trolley when one factor is made variable for one set of experiment.

To see if friction between the runway and the wheels of the trolley make any difference, I could use carpet lined runway for high resistance due to more unrefined fibres and a perpex or glass runway for low resistance due to its smoother surface. The rougher surface will provide more friction and thus allow me to see the extant to which it will slow down the trolley.

To see the effect of mass I can use a large and a small trolley of different mass, instead of adding mass into the trolley, and see how it affects the speed as to whether the speed is increased by a greater mass as compared to a smaller mass.

To see the effect of the contact area, I could use a trolley with less number of wheels (small contact area) and one with large number of wheels  (large contact area). The smaller contact area means that the friction between the wheel of the trolley and the runway would be less.

These further experiments will show which other factors that affect the speed of a trolley when released from a height.

BIBLIOGRAPHY

1. Google.co.uk- Physics   Factors affecting the speed of a trolley on a ramp
2.  Letts A-level guide to Physics   (2000)
3. Ask Jeeves.com   Factors affecting the speed of trolley on a ramp  (2003)

4.         New Book of knowledge   (1998).