Question

5. Class II lovers are designed to have
(a) MAVR
(b) MAVR
(6) MAI
(d) MA1
Ans. MA >
NUMERICALS
1
A crowbar of length 120 cm has its fulcrom stated
at a distance of 20 cm from the load Calculate the
mechanical advantage of the crowbar Ans.
2 A pair of scissors has its blades 15 cm long, while
its handles are 75 cm long. What is its mechanical
An 0.5
3. A force or 5 kgf is required to cut a metal sheet. A pair
of shears used for cutting the metal sheet has its blades
5 cm long, while its handles are 10 cm long. What
effort is needed to cut the sheet? Ans. 25 kgf
4. Fig. 3.16 below shows a lever in use,
(a) If a weight Wis placed ut odio of 250 cm
from the support on the tower arm tone
the red, find w
b) If a weight 5 kgf is kopt te balance the rod.
find its position
(c) To which class of lever does it belong
Ans.(*) 4 32 kgf (b) at dine 26 m
from the support on longer am ) 1
3. A lever of length 9 cm has its ond arm 5 cm long
and the effort arm is 9 cm long (a) To which can
does it belong? (b) Draw a diagram of the lever showing
the position of the futurum F and directions of both
the loud L and effort E. (c) What is the mechanical
advantage and velocity ratio if the efficiency is 100%
(d) What will be the mechanical advantage and velocity
ratio if the efficiency becomes 50%
Ans.(a) class II (c) MA = 18. VR =
(d) MA = 09. VR = 18
9. Fig. 3.17 below shows a lever in se 2018
advantage
Fig. 3.16
(a) To which class of lever does it belong?
(b) If AB Im AF- 0.4 m, find its mechanical
advantage
(c) Calculate the value of E.
Ans.(a) Class I (b) 15 (c) 10 kgf
$. A man uses a crowbar of length 1.5 m to raise a
load of 75 kgf by putting a sharp edge below the bar
at a distance of 1 m from his hand, (a) Draw a
diagram of the arrangement showing the fulcrum (F).
load (L) and effort (E) with their directions, (h) State
the kind of lever. (c) Calculate (i) load arm,
(ii) effort arm, (ii) mechanical advantage, and
(iv) the effort needed.
Ans. (b) class I (c) (i) 0.5 m (in) 1-0 m
Cili) 2 (iv) 37.5 kgf
6. A pair of scissors is used to cut a piece of cloth by
keeping it at a distance of 80 em from its rivet and
applying an effort of 10 kgf by fingers at a distance
of 20 cm from the rivet
(a) Find : (i) the mechanical advantage of the
scissors, and (1) the load offered by the cloth
(b) How does the pair of scissors act as a force
multiplier or as a speed multiplier ?
Ans.(a) (i) 0.25 ( 25 kgf. (b) speed multiplier
A 4 m long rod of negligible weight is supported at
a point 125 em from its one end and a load of
18 kgf is suspended at a point 60 cm from the
support on the shorter arm
Fig. 3.17
(a) To which class of levers does it belongs?
(b) Without changing the dimensions of the lever.
the load is shifted towards the fulcrum what
happens to the mechanical advantage of the
lever?
Ans. (a) It belongs to second class lever
(b) The mechanical advantage of the lever will increase
when load is shifted towards the folorum
10. Fig. 3.18 below shows a wheel barrow of mass
15 kg carrying a load of 30 kgf with its centre of
gravity at A. The points B and C are the centre of
wheel and tip of the handle sach that the horizontal
distance AB = 20 cm and AC = 40 cm
С
( 20cm
Fle. 3.18
Find : (a) the load arm, (b) the effort arm, tc) the
mechanical advantage, and (d) the minimum effort
required to keep the leg just off the ground
Ans. (a) 20 cm (b) 60 cm, (c) 3 (d) 15 kgf
59

Answer 1

Answer:

d

Explanation:

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