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Syllabus
Q). In Fig. 1.34, a uniform bar of length l m is supported at its ends and loaded by a weight W kgf at its middle. In equilibrium, find the reactions at the ends.
Q(b) (i). Diagram alongside shows a nut cracker with a wooden base. If the effort required to crack the nut is 50 N, find the resistance offered by the nut.
(ii) What force should be directly applied on the nut , so as to crack it without the help of nut cracker ?
Q9. A block A, weighing 100 N, is pulled up a slope of length 5 m by means of a constant force F (= 100 N) as illustrated in Fig. 2.15.
(a) What is the work done by the force F in moving the block A, 5 m along the slope?
(b) What is the increase in potential energy of the block A ?
(c) Account for the difference in the work done by the force and the increase in potential energy of the block.
(a) useful force exerted by the engine in newton.
[Ans. 750 N]
(b) power developed in kilowatt at 54 km/h
Assume that all frictional forces are absent.
[Ans. 11.25 kW]
Q.18. A uniform metre scale is balanced at 40 cm mark, when weights of 20 gf and 5 gf are suspended at 5 cm mark and 75 cm mark respectively. Calculate the weight of metre scale.
[Ans. 52.5 gf]
Q.16. The adjacent diagram (Fig. 1.27) shows a heavy roller, with its axle at O, which is to be raised on a pavement XY. If there is friction between the roller and pavement, show by an arrow on the diagram the point of application and the direction of force to be applied.
Q.5. A sign weighing 98 N is suspended from the middle of a 4 m long chain. The ends of the chain are attached to a ceiling at points 3 m apart. Determine the tensions in the chains.
Q.(b) A ball of mass 15 g is thrown vertically upwards with initial velocity of 20 At what height above the ground the ball would have equal potential and kinetic energy? [Take g = 10 ]
Q.16. In fig. if the surfaces are frictionless the ratio is -
(1) : 2
(2) 1 :
(3) 1 : 5
(4) 5 : 1
Q5. The wheel shown in the diagram (Fig. 1.17) has a fixed axle passing through O. The wheel is kept stationary under the action of (i) a horizontal force F1 at A and (ii) a vertical force F2 at B.
(a) Show the direction of force F2 in the diagram.
(b) Which of the force F1 or F2 is greater?
(c) Find the ratio between the forces F1 and F2. Given : AO = 2.5 cm, BO' = 1.5 cm and O'O = 2.0 cm.
16. A boy takes 3 minutes to lift a 20 litre water bucket from a 20 m deep well, while his father does it in 2 minutes. (a) Compare : (i) the work, and (ii) power developed by them. (b) How much work each does ? Take density of water = 103 kg and g = 9.8 N k.
Ans. (a) (i) work 1 : 1, (ii) power 2 : 3, (b) work done by each = 3.92 kJ
Question: what is the average of all these distances?
That is to say, what is the time average of the distance traveled?
Question l.
(a) A brass ball is hanging from a stiff cotton thread. Draw a neat labelled diagram showing the forces acting on the brass ball and the cotton thread.
(b) The distance between two bodies is doubled. How is the magnitude of gravitational force between them affected?
suspended by a weightless string at the 0.3 m mark. (i)Draw the diagram of the arrangement. (ii)
Calculate the tensions in the string by which the metre scale is suspended. (Take g = 10 m/s2
)
Q24. A ball of mass 1 kg is dropped from a height of 7 m and rebounds to a height of 4.5m. Calculate:
(a) its kinetic energy before the impact and
[ Ans. 70 J]
(b) its initial rebound velocity and kinetic energy,
[Ans. 11.8 m s–1 and 45J]
(c) the loss of kinetic energy.
[Ans. 15 J]
Q.15. Explain the following:
(a) Why is it easier to pull down the branch of a tree from its free end than from anywhere else?
(b) Why do we use a long handle with a screw jack?
(c) Why do we use a long spanner to open a tight nut?
(d) Why is the upper stone of a hand flour grinder provided with a handle near its rim?
Q.(e). A metal ball of mass 60 g falls on a concrete floor from a vertical of 2.8 m and rebounds to a height of 1.3 m. Find the change in K.E. in S.I. units.
Q(c). The diagram below shows a lever in use:
(i) To which class of levers does it belong ?
(ii) Without changing the dimensions of the lever, if the load is shifted towards the fulcrum what happens to the mechanical advantage of the lever ?
9. A block and tackle system has the velocity ratio 3. Draw a labelled diagram of the system indicating the points of application and the directions of load and effort. A man can exert a pull of 200 kgf. What is the maximum load he can raise with this pulley system if its efficiency is 60%?
Ans : 360 kgf
Please do not provide any link.
PS : Sir PLEASE explain each step because I didn't understand all the steps in a solution given for this same sum earlier.PLEASE DONT GIVE A LINK TO A SIMILAR ANSWER .....Thanks