Kinetic & Potential Energy
Name: Corinne Chen
Block: 1 – 3
Date: May 22nd, 2013
Purpose: To investigate and compare the potential energy, kinetic energy and speed of a cart on a hill 1 kg
h 1 m
Materials: 1. 2. Cart & 1 kg mass 3. Board 4. Timer 5. Metre ruler 6. Tape
Data Table: With 1 kg mass: Trial # | Distance(m) | Time(s) | 1 | 1m | 0.41s | 2 | 1m | 0.45s | 3 | 1m | 0.44s | Without 1 kg mass: Trial # | Distance(m) | Time(s) | 1 | 1m | 0.42s | 2 | 1m | 0.48s | 3 | 1m | 0.45s |
Calculations:
With 1 kg mass: Average time = 0.4333s Average velocity = Distance ÷ Average time = 1m ÷ 0.4333s ≈ 2.308m/s Total mass = (7.5N ÷ 9.8N/kg) + 1kg ≈ 1.765kg Height = 0.33m Kinetic energy = ½ mv2 = ½ × 1.765kg × (2.308m/s)2 ≈ 4.70J Potential energy = mgh = 1.765kg × 9.8N/kg × 0.33m = 5.71J Without 1 kg mass: Average time = 0.45s Average velocity = Distance ÷ Average time = 1m ÷ 0.45s ≈ 2.236m/s Mass = 7.5N ÷ 9.8N/kg ≈ 0.765kg Height = 0.33m Kinetic energy = ½ mv2 = ½ × 0.765kg × (2.236/s)2 ≈ 1.91J Potential energy = mgh = 0.765kg × 9.8N/kg × 0.33m = 2.47J
Analysis Questions:
How did the potential and kinetic energy compare (top and bottom of the hill)? Explain using law of conservation of energy. (use values of KE and PE for cart with mass attached)
According to the law of conservation of energy, in an isolated system, the initial potential energy and the kinetic energy should be the same. However, when we were doing the experiment, we could not guarantee for ideal situation with no extra resistance, so the data above, which shows that there is difference between the two