The experiment safe Essay
The experiment safe
In every day lives we come across a number of different objects that are bouncing, colliding and in motion. All these are attributable to the energy changes involved in the process thus obeying the law of conservation of energy. The law of conservation of energy states that ‘energy can neither be created nor destroyed’ and that the sum total of energy in this universe remains constant. This scientific method of looking at energy changes can be associated and implemented on a variety of simple things and one among them being observation of bouncing objects.
This motivation has lead me to investigate, understand and analyse bouncing of a ball on a surface. However, understanding the bouncing mechanism is not as simple as it appears, because there are several factors involved during the bouncing action. For example, the material of the ball, the type and nature of surface over which it freely falls, frictional factors due to air resistance, temperature affecting the surrounding air molecules as well as during the ball-surface interactions. Preliminary Investigation Looking around practically made me notice a variety of different types and sizes of balls.
There were golf balls, tennis balls, footballs, sponge balls, cricket balls, bouncy balls, etc. I observed them carefully and noticed that none were similar in any way. The cricket balls were the only ones made out of leather, the bouncy balls were made out of dense rubber, and the golf balls were made of plastic. I tried to test the bounce of these balls on different surfaces like carpeted flooring and wooden flooring. I found that each ball when dropped on these flooring was bouncing to different heights. I felt that each of these balls when dropped on a given flooring surface had different factors that influenced their bounce.
Also I noticed that the ball being dropped constantly bounced almost at the same height. This made me feel that I could use this as my chosen experiment for further investigations. As mentioned earlier, the bouncing of balls may look simple, but the energy conversions are quite complex. In simple terms, the work done during a bouncing ball system involves three possible energy sources, 1) Gravitational potential energy (energy due to its position) 2) Kinetic energy (energy due to its motion) 3) frictional energy (lost due to production of heat and sound).
The ball acquires Gravitational Potential Energy because of its position and also the ball is working against the gravity to acquire this position. Kinetic energy is gained during the motion of the ball. The frictional energy is lost due to the production of heat and sound. In fact, the conversion of the potential energy results in the kinetic energy of motion until the bounce is over and this potential energy is regained as ball acquires the next position or height. However, on each bounce over a given surface energy of impact is transferred to the surface on which it bounces. Also energy is used up in over coming the air resistance.
The energy of impact can be split into sound energy, heat energy or light energy (spark) in the case of very heavy balls (for ex. Iron balls striking iron plate surfaces). This can be totally called as frictional energy loss. The process of bouncing continues with frictional loss occurring on each bounce and this effect could be known as damping. Damping means the loss of height on each bounce on a given surface. The damping effect decreases until the ball attains the minimum potential energy. The damping effect influences the speed and so it tends to slow down the ball each time it impacts the surface.
To observe this effect experiments were planned to drop large bouncy balls on different surfaces and to note the rebound heights. Preliminary Results Bounce Quality Number Balls used Carpet flooring Wooden flooring 1 Golf Ball Low Medium 2 Tennis Ball Medium Medium 3 Football Low Low 4 Sponge Ball Low Low 5 Cricket Ball Low Low 6 Bouncy Ball Medium High Below are the formulae of different types of energy and work done: Potential Energy: PE = mgh 1) Where, m= mass of the ball (kg) g= acceleration due to gravity () h= height of the bounce(m) Work Done: Wd = F x d -(2) Where,F= Force (N) d = bounce height (m) Also as part of my preliminary work I did some work using a CD Called ‘Science Investigations’.
This was very useful as I could see how the ball rebound height would differ if I changed the temperature of the ball. The ball being used was a squash ball. The results I gained were as follows (assuming that the drop height was kept the same-1metre): Temperature(i?? C) Rebound height(cm) (The rebound height was measured from the bottom of the ball. ) As you can see, these results seem fairly realistic and accurate.
As the temperature inside the squash ball increased, the rebound height increased. This was the case in all of the tests. Also using this CD I could investigate the different amounts of energy bring used up when a ball bounces. A ball has 100% gravitational potential energy when it is in your hand. As soon as you release it the amount of gravitational potential energy decreases and instead, 100% Kinetic energy is formed. However, when the ball hits the ground there is no kinetic energy or gravitational potential energy. Instead, there is only elastic potential energy and heat/sound energy.
After the ball hits the ground, kinetic energy is regained again, but it is not a full 100%, it is only 80%. 20% of the energy was used up as heat/sound energy. So when the ball is caught in your hand again, the gravitational potential energy returns, but there is only 20% of what there previously was, so the ball does not reach its drop height. Safety: To make the experiment safe, I will have to make sure of the following: > That the nail that supports the ball is tightly secured in its position. > That the balls are used in a proper manner in all situations. > The equipment like the clamp and stand are fixed to the workbench securely.
To make this test fair I will have to make sure of the following: > That the metre rule is straight and not at an angle. > That I release the ball from the given point. E. g. Place the bottom of the bouncy ball in line with the one metre mark, the 0. 8 metre mark etc. > Just release the ball without adding any extra force. > Keep the temperature in the room constant. > Make sure that there is very little air movement. > Make sure that you have the same experimental conditions for all the three trials. The factor I will be investigating is the height I drop the ball.
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