Question
Explain why, frictional force is said to be a contact force.
✓
Answer
If life an object which is moving over a horizontal surface does not continue with constant velocity when the accelerating force is removed. Instead the object slows down and eventually stops. The deceleration is caused by a frictional force between the object and the surface on which it travels. A frictional force always acts to oppose the motion of an object over a surface and is an example of a contact force. When we try to slide one object over another, we find that there is a force which opposes the motion. This force is called friction. Whenever there is relative motion of two surfaces in contact, there is frictional resistance. When a body moves over another, it has to overcome friction. This needs energy. Hence, some energy is always wasted in overcoming friction. When two parts of a machinery rub against each other heat is produced, and the efficiency of the machine decreases. There will be a greater wear and tear in the different parts of a machine due to friction.
Need a full question paper?
Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.
Explore more
Similar questions
What is irrigation? Why is irrigation necessary?
What is petroleum? Where does petroleum occur?
Write the names of the main parts of the human eye.
Name three liquids which when tested in the manner shown in figure given alongside may cause the magnetic needle of compass to deflect.
What is an earthquake? What are the two main situations in which earthquakes occur?
Draw a labelled diagram of the human eye. Label the following parts on this diagram: Cornea, Iris, Pupil, Ciliary muscles, Eye-lens, Retina, Optic nerve, Blind spot.
The substance W is a fossil fuel. It occurs deep below the ground in certain areas of the earth. Another fossil fuel X is found trapped above the deposits of W. When W is subjected to a process called Y, then a number of different products are collected at different temperature ranges which are put to different uses. A special grade of product Z obtained in this way is used as aviation fuel in jet aeroplanes.
- What are (i) W, and (ii) X ?
- What is the physical state of (i) W, and (ii) X ?
- Name the process Y.
- Name the product Z.
Give an example to show that friction depends on the force with which the two surfaces are pressed together.
Draw a neat, labelled diagram of nitrogen cycle in nature. Which natural phenomenon occurring in the sky is responsible for nitrogen fixation?
What type of combustion is represented by:
- Burning of white phosphorus in air at room temperature?
- Burning of LPG in a gas stove?
- Ignition of a cracker?
- Burning of coal dust in a coal mine?