To Find the Downward Force, Along an Inclined Plane, Acting on a Roller due to Gravitational Pull of the Earth and Study its Relationship with the Angle of Inclination θ by Plotting Graph Between Force and sin θ.
Physics Lab ManualNCERT Solutions Class 11 Physics Sample Papers
To find the downward force, along an inclined plane, acting on a roller due to gravitational pull of the earth and study its relationship with the angle of inclination θ by plotting graph between force and sin θ.
An inclined plane, A trolley or roller, pan, weight box, spring balance, spirit level, strong thread, half metre scale.
If total weight W1 – M1 g moves the body up and total weight W2 – M2 g makes the body move down, then downward force acting on the body along the inclined plane,
- Test the pulley of the inclined plane and see that it is free from friction. Oil it, if necessary.
- Keep the apparatus on table with the slot portion of the base beyond the edge of the table.
- Make the base of inclined plane horizontal (test by spirit level) and make it stable (by putting paper pieces if necessary).
- Bring the inclined plane to horizontal position (touching the base). The angle of inclination is now zero (as indicated by protractor).
- Find the weight of the roller by a spring balance and place it on the inclined plane in the middle.
- Tie one end of a thread to the roller placed on the inclined plane and pass it over the pulley.
- Pass the thread through the slot in base.
- Find the weight of the pan by spring balance and tie it to free end of thread, keeping the thread free from board.
- Raise the inclined plane and fix it at an angle of 30°. The roller may start rolling down with acceleration.
- Put weights on the pan and increase them till the roller just starts moving upward with uniform velocity only on tapping. Note the total weights in pan.
- Remove some small weights from weights in the pan till the roller just starts moving downward with uniform speed only on tapping. Note the total weights in pan.
- Increase the angle of inclination in steps of 5° each, making it 35°, 40°, 45°, 50°, 55° and 60° and repeat steps 10 and 11.
- Record your observations in table as given below.
Least count of spring balance = ………..g wt.
Zero error of spring balance (e) = …………g wt.
Zero correction of spring balance (c) = (- e) = ……….g wt.
Observed weight of the roller (w0) = …………g wt.
Corrected weight of the roller (w = mg) = (w0 + c)
= ………..g wt.
Observed weight of the pan (p0) = ………..g wt.
Corrected weight of the pan (p) = (p0 + c) = ………..g wt.
Table for angle of inclination and weights in pan
- Downward force on the body of weight w = mg comes to be mg sin θ.
- Graph between sin θ and W comes to be a straight line. Hence, W °c sin θ.
- Pulley should be friction less.
- Base should be stable and horizontal.
- Thread should not touch the board or table.
- Inclined surface should be clean, dry and smooth (use glass top).
- Weights in pan should be increased or decreased in small steps.
- Weights should be noted only when the roller just starts moving up or moving down.
Sources of error
- The pulley may not be friction less.
- Spring balance may not be accurate.
- Protractor graduations may not be correct.
Question.1. What is an inclined plane ?
Answer. It is a wooden plane made smooth by putting a glass sheet over it and makes an angle with the horizontal ground.
Question.2.What is relation between downward force and angle of inclination of the plane ?
Answer. The relation is, W-mg sin θ, which is the component of the weight of the body down the inclined plane.
Question.3.What is the normal reaction on the inclined plane ?
Answer. The normal reaction is mg cos θ. There is no movement in this direction.
Question.4.Why is the glass plate fixed at the top of the inclined plane ?
Answer. To make the inclined plane smooth.
Question.5.Name the few application of an inclined plane.
Answer. Inclined plane is a simple machine which makes the work easier. The following are the applications in
(i) Ramp of house
(iii) A plank put at the back of a truck or a railway wagon for loading and unloading heavy goods.