Q161. A particle is projected with a velocity 'u' in a direction at an angle of 45o to the horizontal. It will move perpendicular to the direction of projection after the following time–
A 2u/g
B 2 u g
C u/g
D 2u/g
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Correct answer: 2u/g
Q162. The range of a projectile on horizontal plane is four times of its maximum height. Then angle of projection is
A 30o
B 45o
C 60o
D 90o
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Correct answer: 45o
Q163. If two equal and perfect elastic spheres impinge then their velocities in the direction of centre of line are
A Interchangeable
B equal
C doubled
D None of these
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Correct answer: Interchangeable
Q164. A particle is in equilibrium under three forces, two of the forces act at right angles to one another, one being double the other. Third force has a magnitude of 10 N. Other two have magnitude
A 10,2 10
B 20,2 20
C 10, 20
D None of these
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Correct answer: 20,2 20
Q165. For the catenary y = c cos x h c
A s2 =c2 +y2
B y = c tanψ
C sin x s c h c =
D s=c secψ
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Correct answer: sin x s c h c =
Q166. The frequencies of the values 0, 1, 2, 3, …,n of a variable are given by n n n 1 n n 2 2 n 1 2 q, C q.p, C q.p,...,p − − then the mean of the variable will be (where p+q = 1)
A nq
B np
C n(p+1)
D n(q–1)
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Correct answer: np
Q167. A ship moving at a velocity of 12 km/hour towards north observes, another ship which is 10 km east of this ship and moving with velocity of 16km/hour towards west. After some time they are at the minimum distance from each other. What is the minimum distance between them at this time?
A 2 61km
B 8km
C 6km
D 4km
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Correct answer: 6km
Q168. The horsepower of an engine which lifts 300 kg water per second from the depth of 100 metre is
A 300
B 350
C 380
D None of these
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Correct answer: None of these
Q169. A stone falls from the rest from some height and reaches the earth in 5 seconds. If after 3 seconds of fall the stone is stopped and again allowed to fall, then how much time will it take to reach the ground?
A 3sec
B 4sec
C 4.5 sec
D None of these
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Correct answer: 4sec
Q170. The extremities of a heavy string of length 2l and weight 2lw, are attached to two small rings which can slide on a fixed wire. Each of these rings is acted on by a horizontal force equal to lw. The distance between the rings is
A () 2 log 1 2 l −
B () 2 log 1 2 l +
C () log 1 2 l +
D () log 1 2 l −
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Correct answer: () log 1 2 l +
Q171. The reverse effective forces acting on each particle of a body and the external forces of the system are
A infinite
B in equilibrium
C equal to each other
D None of these
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Correct answer: in equilibrium
Q172. Moment of inertia of an elliptic area of mass M and semi-axes a and b about diameter of length 2r is
A 2 2 2 1 a b M 4 r
B 2 1 ab M 2 r
C 2 1 ab M 4 r
D 2 2 2 1 a b M 2 r
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Correct answer: 2 2 2 1 a b M 4 r
Q173. The centre of gravity (C.G.) of a solid figure formed by revolving a quadrant of ellipse about its minor axis is
A 3b x 0,y 8 =
B 3a x, y 0 8 =
C 3a 3b x, y 8 8 =
D x a,y b =
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Correct answer: 3b x 0,y 8 =
Q174. Three forces, P, Q and R act along the sides BC, CA and AB of a triangle ABC taken in order. If their resultant passes through the centroid of the triangle ABC, then
A P Q R 0 a b c + + =
B R P Q c a b = +
C P Q R a b c =
D None of these
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Correct answer: P Q R a b c =
Q175. Moment of inertia of a solid sphere of mass 'm' and radius 'a' about its tangent is
A 7 5 ma2
B 2 5 ma2
C 2 3 ma2
D 5 3 ma2
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Correct answer: 7 5 ma2
Q176. If there forces P, Q and R act along the sides BC, AC and AB respectively of the triangle ABC and their resultant passes through the orthocenter of triangle, then
A 0 cos cos cos + + = P Q R A B C
B 1 cos cos cos + + = P Q R A B C
C cos cos cos = P Q R A B C
D None fo these
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Correct answer: 0 cos cos cos + + = P Q R A B C
Q177. A particle is projected with a velocity u so that its range on a horizontal plane is twice the greatest height attained then the range is
A 2 u g
B 2 3 u g
C 2 4 5 u g
D 2 g u
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Correct answer: 2 4 5 u g
Q178. A ball is dropped from a height h on a horizontal plane, bounces up and down and finally comes to rest. The total distance described is
A ∞
B 2h
C 2 (1) + h e
D 2 1 + − e h e
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Correct answer: 2 1 + − e h e
Q179. A uniform chain of length l is suspended from two points A and B in the same horizontal line. If the tension at A is twice that at the lowest point of the chain, then the span AB is
A 1 log(1 2) 2 +
B 1 log(2 3) 3 +
C 1 log(2 3) 2 −
D 1 log(1 2) 3 −
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Correct answer: 1 log(2 3) 3 +
Q180. The moment of inertia of any triangular area ABC about a perpendicular to its plane through A is
A 2 2 2 (3 3) 12 + − M b c a
B 2 2 2 () 12 + + M a b c
C 2 2 2 [ ] 12 − − M a b c
D 2 2 2 [3 3 2 ] 12 + + M a b c
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Correct answer: 2 2 2 (3 3) 12 + − M b c a