# How the height of a ramp affects the speed of a toy car.

Physics investigation.                                      Laura Boyes 11D1.

How the height of a ramp affects the speed of a toy car.

Background knowledge.

Speed is a way of describing how fast an object is moving and can be calculated if you know the distance the object travels and how long it takes to travel that distance. You can then calculate the speed of an object using the formula:

SPEED (M/S) = DISTANCE TRAVELLED (M)

TIME TAKEN (S)

The formula triangle for this is;

Speed is measured in metres per second (m/s), kilometres per hour (km/h) or miles per hour (mph).

There are certain factors, which affect the stopping distance of a car such as gravity and the surface area, which it travels on. If the gravity is decreased this would affect the friction between the car and surface area and so it would decrease the stopping distance of a car. Different surface areas are harder for the car to overcome for example sand is rough and has a greater resistance so the car would need more energy to travel over sand than a smooth surface. Velocity is a similar thing to speed, it is the speed of an object in a certain direction, to work out the velocity you need to know the speed and the direction in which it is travelling, so a car travelling south at a speed of 20 mph has a velocity of 20 mph south. Acceleration is a rate of change in velocity. It is the rate at which an object’s speed is increasing or decreasing. To work out the velocity of an object we need to know the change in velocity and the time taken for the change in velocity. Acceleration is measured in metres per second squared ( m/s²). During my experiment there will be certain forces acting on the car, When the car is stationary there is a downward force exerted by the weight of the object and an upwards force exerted by the surface. When the toy car is moving down the ramp there will be a force working in the opposite direction to the movement of the car, this is called friction. When the car is moving at a steady pace the friction force is balanced, friction is useful to prevent a car from skidding down a hill however the force may not be great enough to prevent this happening in my experiment, this may cause the car to skid slightly.

When a car is placed at the top of the ramp, it gains a certain amount of potential energy - this is converted into kinetic (movement) energy as the car moves down the slope.  The more potential energy the car has, the faster it will move down the ramp. Kinetic energy depends on the mass of an object and the speed of the object, as a moving car has both of these when it moves with a greater speed it has more energy providing it’s mass ahs not changed.  The only factors that can affect this experiment are the height, the mass and the gravity. The gravity will always be the same so I will use another factor as the variable. There will always be forces that could slightly affect the result, such as friction between the ramp and the cars wheels, and air resistance. There is no way I can control any of these factors, but they shouldn’t affect the result too much.

When the gravitational potential energy is converted into kinetic (movement) energy as the car moves down the ramp, the friction between the wheels of the car and the surface of the ramp may use some of the energy; this can slow down the car, but only very slightly. The friction will not affect the results if there is the same amount of friction each time, to do this I will use the same car and ramp each time.

Prediction.

My prediction ...