Physics ICSE Class 7 Important Questions Chapter 3 Energy
Additional Questions
A. Tick (√) the following questions.
Question 1.
The ability to do work is called
(a) power
(b) energy
(c) efficiency
(d) potency
Answer:
(b) energy
Question 2.
Machines help us to
(a) do work
(b) save effort
(c) save time
(d) all of these
Answer:
(d) all of these
Question 3.
Some machines are simple and some machines are –
(a) bad
(b) good
(c) costly
(d) complex
Answer:
(d) complex
Question 4.
Simples machines can be as simple as –
(a) needle
(b) thread
(c) door knob
(d) both (a) and (c)
Answer:
(d) both (a) and (c)
Question 5.
Pulley, wheel, wedge and screw are
(a) simple machines
(b) complex machines
(c) any of (a) and (b)
(d) none of these
Answer:
(a) simple machines
Question 6.
A factor by which force applied is multiplied by a machine is called
(a) safety factor
(b) multiplying factor
(c) mechanical advantage
(d) addition factor
Answer:
(c) mechanical advantage
Question 7.
Levers can be classified mainly into
(a) one type
(b) two types
(c) three types
(d) four types
Answer:
(c) three types
Question 8.
Incline plane is
(a) a complex machine
(b) a simple machine
(c) not a machine
(d) none of these
Answer:
(b) a simple machine
Question 9.
Formula for mechanical advantage is given by load x load arm =
(a) pivot x pivot arm
(b) efficiency
(c) power
(d) effort x effort arm
Answer:
(d) effort * effort arm
Question 10.
Mechanical advantage is also known as
(a) leverage
(b) addition factor
(c) chemical advantage
(d) electrical advantage
Answer:
(a) leverage
Question 11.
The pivot point of a lever is known as
(a) Axis
(b) axle
(c) fulcrum
(d) Axes
Answer:
(c) fulcrum
Question 12.
Orders of levers are based on
(a) location of pivot point
(b) load
(c) effort
(d) all of these
Answer:
(d) all of these
B. Answer the following questions.
Question 1.
Define energy.
Answer:
Energy is defined as the capacity of doing work. It is the ability to do work.
Question 2.
Express energy in proper units.
Answer:
Unit of energy = Joule
Smaller unit of energy = K cal (kilocalorie)
1 K cal = 1000 cal 1 cal = 4.2 J
Question 3.
Discuss about different forms of energy.
Answer:
Different forms of energy include :
(a) Potential energy : This form of energy is due to position of the object.
(b) Kinetic energy : This form of energy is due to motion of an object.
(c) Electrical energy
(d) Thermal energy
(e) Light energy
(f) Sound energy
Question 4.
Describe conversion of energy from one form to another in different situation.
Answer:
In bow and arrow. When we pull the string of bow while holding arrow in the pulled string, some potential energy is stored due to change in the formation of bow. On releasing the arrow, potential energy of bow changes into kinetic energy of the arrow. It shoots away due to this energy.
Question 5.
State law of conservation of energy, with example.
Answer:
It states that energy can neither be created nor destroyed, it can only change its form. In other words total energy is conserved during transformation of energy.
Example : A pendulum potential.
C. Tick (√) the best choice :
1. 1 joule =
(a) 2 newton metre
(b) 1 newton metre
(c) 1 newton centimetre
(d) 1 newton millimetre
Answer:
(b) 1 newton metre
Question 2.
Mechanical energy consists of
(a) kinetic energy
(b) potential energy
(c) both (a) and (b)
(d) none of these
Answer:
(c) both (a) and (b)
Question 3.
A stone at height has
(a) kinetic energy
(b) potential energy
(c) any of (a) or (b)
Answer:
(b) potential energy
Question 4.
When fire works are lighted in a celebration then chemical energy changes to.
(a) heat
(b) sound
(c) light
(d) all of these
Answer:
(d) all of these
Question 5.
Electrical energy changes to heat energy in
(a) oven
(b) geyser
(c) toaster
(d) all of these
Answer:
(d) all of these
D. Mark true (T) or false (F).
Question 6.
Ability to do work is energy.
Answer:
True.
Question 7.
International unit of energy is joule.
Answer:
True.
Question 8.
Kinetic energy is due to position of an object.
Answer:
False.
Question 9.
Energy can be destroyed.
Answer:
False.
Question 10.
Energy can be transformed from one form to another.
Answer:
True.
E. Fill in the blanks :
Question 11.
Potential energy is due to of a body.
Answer:
Potential energy is due to position of a body.
Question 12.
Pendulum of a wall clock has energy.
Answer:
Pendulum of a wall clock has mechanical energy.
Question 13.
When work is done on an object, its energy
Answer:
When work is done on an object, its energy is transferred.
F. Define :
Question 14.
Energy
Answer:
Energy is defined as the capacity of doing work. It is the ability to do work.
Question 15.
Unit of energy
Answer:
Work of 1 joule is said to be done when a force of 1 newton moves an object through a distance of 1 metre in the direction of the force.
Question 16.
Potential energy
Answer:
This form of energy is due to position of the object. Work done to change the position of an object is stored as potential energy in the object.
Question 17.
Kinetic energy
Answer:
This form of energy is due to motion of an object. The word kinetic means ‘producing movement’.
Question 18.
Mechanical energy
Answer:
The sum of potential energy and kinetic energy possessed by a body is called mechanical energy.
G. Match the following :
Question 19.
| (a) light to chemical | (1) electrical-motor |
| (b) electrical to light | (2) Dry cell |
| (c) chemical to electrical | (3) lamp |
| (d) electrical to mechanical | (4) Photosynthesis |
Answer:
| (a) light to chemical | (4) Photosynthesis |
| (b) electrical to light | (3) lamp |
| (c) chemical to electrical | (2) Dry cell |
| (d) electrical to mechanical | (1) electrical-motor |
ICSE Class 7 Physics Important Questions