Download The Galaxy Education System S. N. Kansagra School Sub: Physics

The Galaxy Education System
S. N. Kansagra School
Sub: Physics
Class: X
Chapter 1 – Turning moment, Center of gravity,
Centripetal force, Uniform circular motion
Assignment 2
1. State the condition when a force produces (i) translational motion (ii)
rotational motion in a body.
2. Define moment of force and state its SI unit.
3. Is moment of force a scalar or a vector quantity?
4. State two factors on which moment of force depends?
5. State the formula for finding moment of force.
6. What do you understand by clockwise and anticlockwise moment of force?
7. Why is it easy to open a door by applying a force at its end?
8. The stone of a hand grinder is provided with a handle near its rim. Why?
9. A, B and C are three forces each og magnitude 4 N acting in the plane of
paper as shown in the figure below. The point G lies in the same plane.
(i)
Which force has the least moment about G? Give reason
(ii)
Which force has the largest moment about G? Give reason.
B
A
C
G•
10) A body is acted upon by two forces each of magnitude F, but in opposite
directions. State the effect of the forces if:
a) both forces act at the same point of the body.
b) the two forces act at two different points of the body at a separation r.
11) Draw a neat labeled diagram to show the direction of two forces acting on a
body to produce rotation in it. Also mark the point about which rotation takes
place, by the letter O.
12) What do you understand by the term couple? State its effect. Give two
examples of couple in our daily life.
13) Define moment of couple. State its SI unit.
14) State the principle of moments
In question no 15, 16 and 17, choose the correct alternative:
15) In order to rotate a bar pivoted at its midpoint, we need to apply:
a) a large force at any point on the bar
b) a small force exactly at the midpoint of the bar
c) two equal forces at the two ends, but in the same direction
d) two equal forces at the two ends, but in the opposite direction.
16) A body is acted upon by two unequal forces in opposite direction, but not in
one line. The effect is that:
a) the body will have only rotational motion
b) the body will have only translational motion
c) the body will have neither rotational nor translational motion
d) the body will have rotational as well as translational motion
17) The appliance which works on the principle of moments is:
a)Spring balance
b) Beam balance
c) pendulum clock
d)Balance wheel
18) Define the term ‘center of gravity’.
19) Can the c.g be situated outside the material of the body? Give an example.
20) On what factor does the position of the c.g of a body depend? Explain your
answer with an example.
21) Where is the c.g of (i) triangular lamina (ii) rectangular lamina (iii) circular
lamina?
22) Does the position of c.g of a body remain unchanged even if the body is
deformed?
23) Explain the meaning of uniform circular motion. Give one example.
24) Which physical quantity remains constant in a uniform circular motion?
25) Give an example of motion in which speed remains uniform but the velocity
changes.
26) A uniform circular motion is an accelerated motion. Explain it.
27) Differentiate between a uniform linear motion and uniform circular motion.
28) Name the force required for circular motion. State its direction.
29) What is centripetal force?
30) A piece of stone tied at the end of a thread is whirled in a horizontal circle.
Name the force which provides the centripetal force.
31) What is centrifugal force?
32)A uniform meter rule of mass 100 g is balanced on a fulcrum at mark 40 cm by
suspending an unknown mass m at the mark 20 cm. Find the value of m. To which
side the rule will tilt if the mass m is moved to the mark 10 cm? What is the
resultant moment now? How can it be balanced by another 50 g mass?
33) A uniform meter rule of weight 10 gf is pivoted at its 0 mark. (i) What moment
of force depresses the rule? (ii) How can it be made horizontal by applying a least
force?
34) A physical balance has its arms of length 60 cm and 40 cm. What weight kept
on pan of longer arm will balance an object of weight 100 gf kept on other pan?
35) When a boy weighing 20 kgf sits at one end of a 4 m long see-saw, it gets
depressed at this end. How can it be brought to the horizontal position by a man
weighing 40 kgf?
36) A uniform meter rule balances horizontally on a knife-edge placed at the
58cm mark when a weight of 20 gf is suspended from one end. Draw a diagram of
the rule and find the weight of the rule?
37) A uniform meter rule is pivoted at its mid-point. A weight of 50 gf is
suspended at one end of it. Where a weight of 100 gf should be suspended to
keep the rule horizontal?
38) A uniform meter scale of weight 50 gf carries weights of 10 gf and 60 gf at the
20 cm mark and the 75 cm mark respectively. Where a knife-edge should be
placed to balance the meter scale?
39) A uniform meter scale supported at the 60 cm mark weighs 50 gf. One weight
of 5 gf is suspended at the 92 cm mark. What weights should be suspended at the
20 cm and the 80 cm mark to balance the scale, if the two weights together weigh
59 gf?