# Investigating the Effect of Mass and Speed of a Moving Object on Its Stopping Time The investigation is about the mass and speed of a moving object and how this affects its stopping distance due to the changes in energy needed to brake. Since I cannot measure the speed and energy accurately I shall change the definition of my investigation. The problem/task I will be investigating is how the mass of a moving object ? a trolley, affects its stopping distance. [image] [image] Stopping Distance m In order for a moving vehicle to stop a Braking Force is needed. The friction between the wheel and the ground usually does this. But in this experiment the trolley has no brakes therefore a weight is attached to the trolley to stop it when the string attached to the weight tightens and provides an opposing force to the movement of the trolley. Force is the factor that pushes or pulls an object. Forces can change the speed and direction of an object as well as changing its shape. The size of a force is measured in Newtons (N). Work is done when an applied force moves or acts upon an object, against and opposing a force. Work is equal to the energy transferred and is measured in Joules ? J. The equation for Work is Force x Distance
KE is the type of energy all moving objects transfer is measured in J. The faster the object is moving the more force is needed to stop it. This can be explained by saying that the faster the object is moving the more kinetic energy it has and therefore it will need more work to stop it. According to the conservation law all energy cannot be created or destroyed. Also to stop a movement the same amount energy used to move it must be used to stop it. If it has a greater mass then a greater amount of force is needed to push the object therefore it needs a greater amount of work to stop it. Therefore the work done is equal to the KE. Other factors are the velocity of the trolley and the force. Work = Force x Distance Kinetic Energy = ½ x mass x Velocity2 I can calculate the work needed to stop the car by multiplying the force (weight) by the stopping distance. I can calculate the kinetic energy needed by halving the mass and multiplying it by the velocity squared. If I assume all the energy at the start is used as kinetic energy (none lost to air resistance, heat, etc.) Then I can say the following: Initial kinetic energy ? Work done by brakes ½ x m x v2 ? brake force x stopping distance ½ x m x v2 ? F x S S = ½ x m x v2 F Stopping distance ? Mass. I can say this because of the following. [image][image]S = m x v2 2xF The bracketed part of this equation is a constant. This is why I can say s (stopping distance) is directly proportional to the m (mass). I can use the above knowledge to help me plan what I will do in my experiment. Prediction -???- I predict that as the mass of trolley increases it?s braking distance will increase. I know that the mass and the stopping distance or displacement are directly proportion because of the information above. [image] [image] S = m x v2 2xF The bracketed part of this equation is a constant. This is why I can say s is directly proportional to the m. Using this piece of information I predict that the best fit lone on a stopping distance against mass graph will look like this: [image] The scientific information I used to create the basis of the above prediction came from the page above. Preliminary Work -??????- A preliminary experiment was carried out in order to find the weight to be used as the Braking Force. The apparatus was setup as shown below on the next page. The Apparatus:
Weights (1N each)
Pulley
Trolley
Stool
String
Boards
Balance