2. A scissor is a lever of which kind?
a. first
b. second
c. third
d. none of these.
3. Which of the following work, machines cannot do?
a. Apply force at a convenient point
b. Increase the speed
c. Change the direction of force
d. Produce energy
4. Joule is a unit of
a. Work
b. Energy
c. Work as well as energy
d. Neither of work nor of energy.
5. Petroleum products have energy in the form of –
a. Chemical energy
b. Electric energy
c. Light energy
d. Sound energy
Fill in the blanks: –
1. Tractor is a ___________ machine.
2. Fulcrum is in the middle for levers of the ____________ kind.[second]
3. In the lever of the second kind, ________________is in between the fulcrum and effort.[load]
4. The spade used to lift garbage is a lever of the ______________ kind.[third]
5. The use of planks to lift drums on a truck is an example of ___________________.[inclined plane]
6. In the extended rubber of a catapult ______________ energy is stored.[potential]
Answer the following questions : –
1. What is a machine?
A machine is a device that helps make work easier by either multiplying the force applied, changing the direction of the force, or both. Machines are designed to perform specific tasks efficiently.
2. What is known as a lever?
A lever is a simple machine consisting of a rigid bar that can rotate around a fixed point called the fulcrum. Levers are used to lift or move objects by applying force at one end of the bar, which causes the other end to move and exert force on the object.
3. How are fulcrum, load and effort placed in different kinds of levers?
Lever of the First Kind: Fulcrum is between the load and the effort.
Lever of the Second Kind: The load is between the fulcrum and the effort.
Lever of the Third Kind: The effort is between the load and the fulcrum.
4. What is work? Write the units of work.
Work is done when a force is applied to an object, and the object is displaced in the direction of the applied force. The unit of work is the Joule (J) in the International System (SI).
5. If a body moves a distance of 12 metres on applying a force of 125 newton, compute the amount of work done.
Work (W) = Force (F) × Distance (d)
W = 125 N × 12 m
W = 1500 Joules (J)
Therefore, the amount of work done is 1500 Joules.
6. Define energy. What is the relation between work and energy?
Energy is the ability to do work or cause a change in a system. Work and energy are closely related. When work is done on an object, energy is transferred to or from that object. The work-energy theorem states that the work done on an object is equal to the change in its energy. In other words, work is a means of transferring energy between systems.
7. Write five types of energy. Give examples of each.
Mechanical Energy: Examples – moving car .
Chemical Energy: Found in fuels like gasoline and food.
Thermal Energy: Heat energy, like a boiling kettle.
Light Energy: light bulb.
Sound Energy: ringing bell or musical instruments.
