GENERAL PHYSICS LAB MANUAL Imam Mohammed bin Saud University Science Collage 1 Physics Lab Science Collage-Imam University

Physics 101 Lab Physics Lab Science Collage-Imam University 2 General physics course is mainly about mechanics and electricity. You will perform basic physics experiments. Hope you enjoy your physics lab ….

Lab Rules  All students must attend the lab section.  No food. No drinks.  The lab must be clean at all time.  Ask your teacher to check all electrical circuits before turning on the power supply.  Before making any adjustments on your electrical circuit make sure it is turned off.  At the end of each lab switch off and unplug any electrical equipment and disconnect all circuits and arrange all equipment tidily on the bench.  Lab reports must be submitted in a week’s time.  Lab reports writing must be an individual effort although the experiments will be performed in groups.  The lab is worth 20% of the course’s grade.  A missed lab will receive a zero grade.  A make up lab must be performed during the same week of the missed lab if your instructor accepts your excuse. 3 Physics Lab Science Collage-Imam University

Lab report guide Physics Lab Science Collage-Imam University 4 Your lab report should consist of: Title Page: The following information must appear all by itself on the first page: – the title of the experiment – your name – the names of your partners, if any – the performance date – the course and section numbers – the name of your Lab Instructor Introduction: – Objective, method and results. Experimental procedure: – Description of apparatus and outline of technique. Discussion: Here you present your data, explain how you reduced your data to a value for the OBJECTIVE, and reflect on the reliability of your result. Data summary: Present the collected raw data here, in tabular form. Any graphs you created should be included in this section, also. Graphs should be drawn on special graphing paper with appropriate scaling. Graphs, tables and figures must have legible titles and captions.

Lab report guide Physics Lab Science Collage-Imam University 5 Analysis: Describe, in one paragraph, the mathematical steps used to convert the raw data into the final value reported for the objective. Errors: In a single paragraph comment on the accuracy and precision of the apparatus and include a discussion of the experimental errors and an estimate of the error in your final result. The two principal sources or error are: – Physical phenomena similar to the phenomena being measured that affect the measured quantity (e.g., stray magnetic or electric fields, unaccounted for friction). – Limitations of the observer, the analysis and/or the instruments. Conclusion: Restate your results, including the uncertainty in any numerical results. Compare your result with the accepted value. Appendices: Include here the answers to questions assigned from the lab manual. They should be answered in complete sentences using appropriate scientific terminology.

Experiment 1 Balancing force (force table) Objective: Using the force table to experimentally find the balancing force of two forces. Theory: Forces are vector quantities which have both magnitudes and directions. An object with different forces acting on it is considered in equilibrium when the vector sum of all individual forces acting on it is zero, or in other words when the resultant force acting on the object is equal to zero. 6 Physics Lab Science Collage-Imam University

Experiment 1 Continued An object moving as a result of different forces can be balanced by an equilibrant force which is equal and opposite of the resultant force of all forces acting on it. Where F R is the resultant force and F E is the equilibrant force. 7 Physics Lab Science Collage-Imam University

Experiment 1 Continued There are two methods to fond the resultant force of two forces graphically: 1- Tip to Tail Method: We can add any two forces, F 1 and F 2, by placing the tail of F 2 so that it meets the tip of F 1. The sum, F 1 + F 2, is the vector from the tail of F 1 to the tip of F 2. Note that you’ll get the same vector if you place the tip of F 2 against the tail of F 1. In other words, F 1 + F 2 and F 2 + F 1 are equivalent. 8 Physics Lab Science Collage-Imam University F1F1 F2F2 FRFR

Experiment 1 Continued 2- Parallelogram Method: To add F 1 and F 2 using the parallelogram method, place the tail of F 2 so that it meets the tail of F 1. Take these two forces to be the first two adjacent sides of a parallelogram, and draw in the remaining two sides. The vector sum, F 1 + F 2, extends from the tails of F 1 and F 2 across the diagonal to the opposite corner of the parallelogram. 9 Physics Lab Science Collage-Imam University F1F1 F2F2 FRFR

Experiment 1 Continued Physics Lab Science Collage-Imam University 10 Equipment: Force table – stand base – pulleys – hangers – weights (slotted masses) – strings – center ring – protractor.

Experiment 1 Continued The force table is a circular table that has the angles 0 degrees to 360 degrees inscribed on the edge. Pulleys are placed at different angles with strings attached to a center ring running over the pulleys. Masses are placed on mass hangers attached to the end of the strings to provide the forces needed. By adding the vectors (applied forces), the resultant vector is found. To balance the force table, a force that is equal in magnitude and opposite in direction must counterbalance the resultant. This force is the equilibrant force. 11 Physics Lab Science Collage-Imam University

Experiment 1 Continued Procedure: 1- Your lab instructor will provide you with two different forces (magnitude and direction). Attach suitable slotted masses with the thin strings to the center ring of the force table. Remember that: F 1 =M 1 gandF 2 =M 2 gwhere g=9.8 m/s 2 which is the gravitational acceleration. 2- Consider the direction of each force which is represented by the angle. The force table’s edge will help you identify the angle accurately. 3- In order to balance the ring; a third force should be attached. 12 Physics Lab Science Collage-Imam University

Experiment 1 Continued 4- Record the magnitude and direction of the equilibrium force. 5- Plot both original forces on graphing paper by setting a drawing scale (1 cm = 1 N). 6- Find the resultant force graphically. The magnitude of the force is represented by the length of the vector and should be converted using the scale you have chosen. The direction is represented by the angle which you can measure using the protractor. 7- Now find the equilibrant force which is equal and opposite to the resultant force. 8- Record all values in the following table. 9- Find the percentage error. 13 Physics Lab Science Collage-Imam University

Experiment 1 Continued Data: Percentage Error: 14 Physics Lab Science Collage-Imam University Percentage error Balancing forceForce 2Force 1 experimentallygraphically Magnitude Angle

Experiment 2 Acceleration of Linear uniform motion Objective: To calculate the acceleration of an object moving in a straight line with a constant acceleration using equations of motion. Theory: Equations of motion are used to study the linear motion of a uniformly accelerated body. where: 15 Physics Lab Science Collage-Imam University Displacement or change in positiond: Original velocity, the velocity at the start of the acceleration v o: Final velocity, the velocity at the end of the acceleration. v f: Acceleration, this is a constant accelerationa: Time, this is the time period of the acceleration. t:

Experiment 2 Continued Physics Lab Science Collage-Imam University 16 Equipment: Track – trolley – holding magnet – electronic stop clock – light barrier – pulley – mass hanger – slotted weights – cables.

Experiment 2 Continued Procedure: 1- Set the equipment, use the cable to connect the trolley with the pulley and the hanging mass. 2- You can perform this experiment by using either one or two light barriers. 3- If you are using a holding magnet and one light barrier. Connect the holding magnet to the stop clock and adjust the voltage so that the trolley is held. 4- Put the light barrier at a certain distance. 5- Release the trolley by stopping the magnet and record the time the trolley took to pass the light barrier. 6- Repeat and record the time three times then calculate the average time and the final velocity. 7- Change the distance and repeat the previous steps for each distance. 8- If you are using two light barriers, place each barrier at certain distance and hold the cart at the first barrier then release it and record the time. 17 Physics Lab Science Collage-Imam University

Experiment 2 Continued 9- Repeat and record the time three times then calculate the average time and the final velocity. 10- Change the distance and repeat the previous steps for each distance. 11- Whether you used one or two light barriers, tabulate your data. 18 Physics Lab Science Collage-Imam University Time square s 2 Average Time s Time 3 s Time 2 s Time 1 s Distance m

Experiment 2 Continued 12- Plot a graph between the square time (x-axis) and the distance (y-axis). 13- Draw the best line and find its slope at each graph. 14- Calculate the acceleration from each slope using equations of motion. 15- Find the real value of the carts acceleration using Newton’s second law which states that the force is proportional to the acceleration. F=ma where F could be found from the mass causing the motion of the cart. 16- Find the percentage error of the acceleration. 19 Physics Lab Science Collage-Imam University

Experiment 3 Free fall Objective: To calculate the gravitational acceleration of free falling ball. Theory: Under free fall all objects have the same constant acceleration, which in metric system is equal to 9.8 m/s 2 at sea level. Equations that describe free fall are: where: 20 Physics Lab Science Collage-Imam University Vertical displacementΔy: Original velocity, the velocity at the start of the acceleration v o: Final velocity, the velocity at the end of the acceleration. v f: Acceleration due to gravityg: Time, this is the time period of the acceleration. t:

Experiment 3 Continued Physics Lab Science Collage-Imam University 21 Equipment: Steel ball – contact plate – holding magnet – holding magnet adapter with a release mechanism – electronic stop clock – stand base – rods – scale – connecting leads.

Experiment 3 Continued Procedure: 1- Set the equipment and hold the steel ball using the holding magnet at a certain height. 2- Release the ball and read the time the ball took traveling the vertical distance, then reset the stop clock and reattach the ball and read the time again, you should take three readings of the time then find the average time the ball has traveled. 3- Reduce the height and repeat the previous steps. 4- Tabulate your data. 22 Physics Lab Science Collage-Imam University Time square s 2 Average Time s Time 3 s Time 2 s Time 1 s Height m

Experiment 3 Continued 5- Plot a graph between the square time (x-axis) and the height (y-axis) or displacement of ball. 6- Draw the best line and find its slope. 7- Calculate the gravitational acceleration from the slope using equations of free fall. 8- Find the percentage error. 9- Repeat the previous steps using a different mass ball. 10- State your observation 23 Physics Lab Science Collage-Imam University

Experiment 4 Conservation of mechanical energy Objective: To find the final velocity of an object sliding an incline with constant acceleration using energy conservation law. Theory: Energy is the ability to do work and is measured by Jouls. Mechanical energy has two different forms: Potential energy is the energy an object stores due to its position. The gravitational potential energy is given by: PE = m g h Where m is the mass of the object, g is the gravitational acceleration and h is the height of the object. Kinetic energy is the energy of motion. The kinetic energy is given by: KE = (1/2) m v 2 24 Physics Lab Science Collage-Imam University

Experiment 4 Continued The total mechanical energy E, of any isolated system of objects, is defined as the sum of the kinetic and potential energies: E = PE + KE The principle of conservation of energy could be written as: E i = E f Where E i is the initial energy and E f is the final energy An object on an incline will move down with constant acceleration. Energy conservation law: E i = E f KE i + PE i = KE f + PE f 25 Physics Lab Science Collage-Imam University

Experiment 4 Continued (1/2) m v i 2 + m g h i = (1/2) m v f 2 + m g h f If the object starts from rest, we get: m g h i = (1/2) m v f 2 + m g h f (1/2) m vf2 = m g h i – m g h f (1/2) v f 2 = g h i – g h f From the equations of motion: d = (1/2) (v i + v f ) t If the object starts at rest, we get: v f = 2d / t Which means that the final velocity could be found either by the energy conservation law or by equation of motion. 26 Physics Lab Science Collage-Imam University

Experiment 4 Continued Physics Lab Science Collage-Imam University 27 Equipment: Track – trolley – holding magnet – electronic stop clock – light barrier – cables.

Experiment 4 Continued Procedure: 1- Set the track so that it will become an incline by rising one side of it, use the holding magnet to hold the trolley still. 2- Connect the stop clock with a light barrier and put the light barrier at a certain distance and record the distance that the trolley should travel. 3- Measure the height at the beginning and at the end of the motion of the trolley. 4- Release the trolley and find the time it needs to travel the distance three times and find the average time of traveling. 5- Use the equations to find the final velocity. The two values should be equal. 6- Find the percentage error. 7- Calculate the initial and final PE and KE. 8- Repeat the previous steps by changing the height, the mass and the distance and conclude their effect on energy. 28 Physics Lab Science Collage-Imam University

Experiment 4 Continued Physics Lab Science Collage-Imam University 29 Finalvelocit y Real m/s Finalvelocit y Exp. m/s Average Time s Time 3 s Time 2 s Time 1 s Distance m Height (hi-hf) m Ei=Ef KEf J KEi J PEf J PEi J Error1= Erroe2= Error3= Error4=