Physics 2021 Section 077
Lab 4: Work, Power, and Energy
Introduction:
In this lab, we will be able to explore how a non-constant force (spring force) does work on a
cart to change its kinetic energy. The Work-Energy Theorem will enable us to find the total work
done on the cart and compare it to the change in the cart’s kinetic energy. In addition to that, we
will also find the power exerted by the spring by using the equation Pav = ∆W / ∆t .
Procedure:
PART 1: The Work Done by Friction
1). Level the track. Connect two photogates to the interface and set the Timer. Make sure to
position the photogates far enough apart.
2). Push the cart gently and record the initial and final velocity of the cart at the two photogates.
Record the distance between two photogates. Repeat at least two more times.
PART 2: The Work Done by a Spring
1). Set up motion sensor, force sensor, and photogate. The motion sensor must be at least 20cm
from the cart.
2). Connect all the sensors and photogate to the interface. Zero the force sensor with no spring
attached and set the switch on the motion sensor to the car setting. Record data on Capstone that
display force, velocity from photogate, and position from motion detector.
3). Pull the cart back until there is enough tension in the spring to move the cart but not
overextended. Record in Capstone and release the cart.
4). Create a graph on Capstone. Find area under the curve and record.
Data and Analysis:
PART 1: The Work Done by Friction
Mass of cart +flag = 0.8375 kg
d= 0.845 m
Trial # Vo (m/s) Vf (m/s) W = ∆KE Normal Force(N) µ
(J) Force (N)
1 0.5800 0.4600 0.05226 0.06185 0.007535
2 0.5200 0.3900 0.04954 8.208 0.05863 0.007143
3 0.5100 0.3800 0.04844 0.05733 0.006985
Average 0.007221
Sample Calculation for Trial 1:
W= ∆KE = ½ mv2 = ½ m(V o 2 – Vf 2 ) = ½ (0.8375 kg)((0.5800 m/s)2 – (0.4600 m/s)2) = 0.05226 J
N = m*g = 0.8375 kg * 9.8 m/s2 = 8.208 N
F = W/d = 0.05226 J / 0.845 m = 0.06185 N
µ = Ffriction / N = 0.06185 N / 8.208 N = 0.007535
PART 2: The Work Done by a Spring
Mass of cart +flag = 0.8375 kg
Lab 4: Work, Power, and Energy
Introduction:
In this lab, we will be able to explore how a non-constant force (spring force) does work on a
cart to change its kinetic energy. The Work-Energy Theorem will enable us to find the total work
done on the cart and compare it to the change in the cart’s kinetic energy. In addition to that, we
will also find the power exerted by the spring by using the equation Pav = ∆W / ∆t .
Procedure:
PART 1: The Work Done by Friction
1). Level the track. Connect two photogates to the interface and set the Timer. Make sure to
position the photogates far enough apart.
2). Push the cart gently and record the initial and final velocity of the cart at the two photogates.
Record the distance between two photogates. Repeat at least two more times.
PART 2: The Work Done by a Spring
1). Set up motion sensor, force sensor, and photogate. The motion sensor must be at least 20cm
from the cart.
2). Connect all the sensors and photogate to the interface. Zero the force sensor with no spring
attached and set the switch on the motion sensor to the car setting. Record data on Capstone that
display force, velocity from photogate, and position from motion detector.
3). Pull the cart back until there is enough tension in the spring to move the cart but not
overextended. Record in Capstone and release the cart.
4). Create a graph on Capstone. Find area under the curve and record.
Data and Analysis:
PART 1: The Work Done by Friction
Mass of cart +flag = 0.8375 kg
d= 0.845 m
Trial # Vo (m/s) Vf (m/s) W = ∆KE Normal Force(N) µ
(J) Force (N)
1 0.5800 0.4600 0.05226 0.06185 0.007535
2 0.5200 0.3900 0.04954 8.208 0.05863 0.007143
3 0.5100 0.3800 0.04844 0.05733 0.006985
Average 0.007221
Sample Calculation for Trial 1:
W= ∆KE = ½ mv2 = ½ m(V o 2 – Vf 2 ) = ½ (0.8375 kg)((0.5800 m/s)2 – (0.4600 m/s)2) = 0.05226 J
N = m*g = 0.8375 kg * 9.8 m/s2 = 8.208 N
F = W/d = 0.05226 J / 0.845 m = 0.06185 N
µ = Ffriction / N = 0.06185 N / 8.208 N = 0.007535
PART 2: The Work Done by a Spring
Mass of cart +flag = 0.8375 kg
