Q No: 1 Circle the correct answer. 08 1. ...
Q No: 1 Circle the correct answer. 08
1.
Work done
will be maximum if the angle between the force F and displacement d is.
a)
450
b) 900 c) 1800 d)
00
2.
The
relation between horse power and watt is.
a)
1 hp = 546 watts b) 1 hp = 746 watts c) 1 hp
= 1000 watts d) 1 hp = 946 watts
3.
If mass of
a moving object is doubled, its K.E becomes:
a)
2 times b)
4 times c) 5 times d) 16 times
4.
The
consumption of energy by 60 watt bulb in 2 seconds is:
a)
20 J b)
120 J c) 30 J d) 0.02 J
5.
One kilowatt
hour of work is equal to
a)
0.36 MJ b)
3.6 MJ c) 36 MJ d) 360 MJ
6.
The
original source of tidal energy is:
a)
Moon b)
Earth c) Sun d) Sea
7.
When a
force is parallel to the direction of motion of the body, then work done on the
body is:
a)
zero b) minimum c) infinity d) Maximum
8.
The work
done is said to be negative when force and displacement are
a)
Parallel b)
Anti-parallel c)
Perpendicular d) None
Short
Questions: 2×7=14
1.
Calculate
the work done in kilo joules in lifting a mass of 10 kg (at steady velocity)
through a vertical height of 10 m.
2.
An object
has 1 J of potential energy. Explain what does it mean?
3.
When a
rocket re-enters the atmosphere, its nose cone become very hot. Where does this
heat energy come from?
4.
A girl
drops a cup from a certain height, which breaks into pieces. What energy
changes are involved?
5.
A boy uses
a catapult to throw a stone which accidentally smashes a green house window.
List the possible energy changes.
6.
In which
case is more work done? When a 50 kg bag of books is lifted through 50 cm, or
when a 50 kg crate is pushed through 2m across the floor with a force of 50 N.
7.
Drive the
relation between kinetic energy and work.
Long Questions: 08
1.
What is
meant by absolute potential energy?
2.
A 1000 kg
automobile at the tip of an incline 10 m high and 100 m long is released and
rolls down the hill. What is its speed at the bottom of the incline if the
average retarding force due to friction is 480 N?
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