Introduction

What is potential energy ? : Potential energy is the energy that a body has and not yet being spent.

What is work ? : Work is a force is said to do work when it acts on a body so that there is a displacement of the point of application, however small, in the direction of the force.

What is acceleration ? : acceleration is the rate at which the velocity of a body changes with time.

What is mass ? : more specifically inertial mass, is a quantitative measure of an object’s resistance to acceleration.

What is power ? : In physics, power is the rate at which energy is transferred, used, or transformed.

Power = Work/Time it is expressed in Joule/s or Watts.

Objective

The objective of this practical work is to use a motor in order to pull up weights, which are attached to the motor with a string and a wheel. We would then make various trial with different weights and different power level for the motor. We then analyzed the different results.

Equipment

In order to do these measurements we needed a lot of equipments.

– Lego motor

– String

– Excel

– Lab View

– Wheel

– Weights (250 grams in total)

Trial #1

During the first trial, we recorded data from the weights being pulled up by the motor and observed different information such as speed, battery discharge, the mass of the weight, the power level of the motor, the time and the acceleration. In order to make an average we ran this experiment 6 times for 4 different masses : ( 100g, 150g, 200g, and 250g).

Speed (RPM)	Battery Discharge (mV)	Mass (kg)	Power Level (%)	Time (s)	Acceleration (RPM/s)
93.40	62.83	0.10	75	1.53	61.16
88.76	56.00	0.15	75	1.66	53.50
83.65	71.83	0.20	75	1.78	47.02
79.01	53.67	0.25	75	1.89	41.96

Acceleration (RPM/s)	h (m)	g (m/s^2)	mgh (J)	Power =mgh/t
61.16	0.11	9.80	0.108	0.070411
53.50	0.11	9.80	0.162	0.097429
47.02	0.11	9.80	0.216	0.121112
41.96	0.11	9.80	0.270	0.142681

 

The table height is considered as the origin.

When mass increases the quantity of work and the power increases as well.

According to the data we collected from this trial a relationship between acceleration & mass, and battery discharge & mass becomes apparent.

 

 

 

 

 

 

 

 

 

 

 

As the mass increase the acceleration goes down.

 

 

 

 

 

 

 

 

 

 

 

 

In this case we didn’t get very precise measurements, but according to the graph the voltage usage is increasing. We can admit that in general cases, heavy objects require more energy to move them.

Trial #2

In this trial we realized the same experiment but instead of changing the weights we made the power levels vary with the same weight of 250g with power levels: 45, 55, 65, 75

 

	Speed (RPM)	Battery Discharge (mV)	Mass (kg)	Power Level (%)	Time (s)	Acceleration (RPM/s)
	82.39	27.00	0.25	75	1.86	44.27
	67.19	96.00	0.25	65	1.90	35.46
	52.04	83.00	0.25	55	2.90	17.98
	36.77	69.00	0.25	45	4.19	8.780

h (m)	g (m/s^2)	Work (J)	Power =mgh/t
0.11	9.80	0.27	0.145
0.11	9.80	0.27	0.142
0.11	9.80	0.27	0.093
0.11	9.80	0.27	0.064

 

We notice that the work stays the same. It’s because the distance and the mass never changes.

 

 

 

 

 

 

 

 

 

 

 

 

 

We can observe a negative slope due to an error during the experimentation. Admitting that it is an error, and by analyzing only the 3 first point we could see a positive slope which indicates that more more battery power is used to increase the power level.

 

 

 

 

 

 

 

 

 

 

 

 

 

We can see on this graph that the more power is used the faster the object moves.

 

 

 

 

 

 

 

 

 

 

 

 

When power level increases, time decreases.

Conclusion

We can now conclude by admitting that mass has an important role when it comes to measuring the speed, acceleration, work, and power.