PHYSICS [3 Mark Question Answer]

Taking care of machines : Some of the ways in which machines should be cared for are given below.

1. Machines should be kept in a clean environment, which is free from dust and moisture.
2. When not in use, machines should be kept covered to prevent collection of dust on them.
3. Machines made of iron should be protected from rust by coating them with paint.
4. The moving parts of a machine should be regularly oiled with a good-quality machine oil to reduce friction and wear and tear.

Various functions that a machine can perform are :

• Changing the direction of applied force – Example : When a flag is hoisted with the help of a pulley.
  
  
• Changing the magnitude of applied force – Example : Bottle opener multiplies the applied force and much less effort is required to open the cap.
  
  
• Applying force at a convenient point – Example : In a pair . of scissors, the input force is applied at the handle of the scissors which cuts the paper at the other end of the blade.
  
  
• Changing the speed of an object – Example : While riding a bicycle, force is applied on pedals which multiplies the speed.

An inclined plane is a rigid sloping surface over which heavy loads can be raised or lowered to a certain height or depth. The mechanical advantae of an inclined plane is the ratio of the length of the plank to the vertical height of the load raised. Its value is greater than one. Therefore, an inclined plane acts as a force multiplier. Thus, it can be used to lift heavy loads.

Example : If a heavy box needs to be loaded on a lony, it is far easier to push it over an inclined plane than to lift it up. Steeper the inclined plane, greater will be the effort required to push up the load. Sloping ramps, flyovers, roads on hills and staircases are all examples of inclined planes.

A wedge is a double inclined plane such that the two sloping surfaces taper to form either a sharp edge or a pointed edge. Examples : A knife, an axe, a chisel. In some special cases, the number of inclined planes used can be more than two as well. In such cases, the sloping surfaces generally taper to form either a very sharp or a pointed edge to split or pierce materials. Pins, nails and needles are examples of pointed wedges. The front end of a boat is shaped like a wedge so that it can easily cut across the flowing water. The wedge works on a principle of an inclined plane.