A projectile is fired at an angle θ to the vertical. Its horizontal range will be maximum when θ is
0°
30°
45°
90°
Correct Answer :
C. 45°
Related Questions
A particle is dropped from the top of a tower 60 m high and another is projected upwards from the foot of the tower to meet the first particle at a height of 15.9 m. The velocity of projection of the second particle is
16 m/sec
18 m/sec
20 m/sec
22 m/sec
A load of 500 kg was lifted through a distance of 13 cm. by an effort of 25 kg which moved through a distance of 650 cm. The mechanical advantage of the lifting machine is
15
18
20
26
A body is said to move with Simple Harmonic Motion if its acceleration, is
Always directed away from the centre, the point of reference
Proportional to the square of the distance from the point of reference
Proportional to the distance from the point of reference and directed towards it
Inversely proportion to the distance from the point of reference
A ladder of weight 'w' rests against a smooth vertical wall, and rests on rough horizontal ground, the coefficient of friction between the ladder and the ground being 1/4. The maximum angle of inclination of the ladder to the vertical, if a man of weight 'w' is to walk to the top of it safely, is tan'1 x, where x is
1/4
1/3
3
4
A hoop of radius 3 m weighs 100 kg. It rolls along a horizontal floor so that at its centre of mass has a speed of 200 mm/sec. The work required to stop the hoop is
2 J
4 J
6 J
8 J
The product of mass and velocity of a moving a body, is called
Moment
Momentum
Power
Impulse
A ball which is thrown upwards, returns to the ground describing a parabolic path during its flight
Vertical component of velocity remains constant
Horizontal component of velocity remains constant
Speed of the ball remains constant
Kinetic energy of the ball remains constant
A particle executes a simple harmonic motion. While passing through the mean position, the particle possesses
Maximum kinetic energy and minimum potential energy
Maximum kinetic energy and maximum potential energy
Minimum kinetic energy and maximum potential energy
Minimum kinetic, energy and minimum potential energy
A 2 m long ladder rests against a wall and makes an angle of 30° with the horizontal floor. Where will be the instantaneous center of rotation when the ladder starts slipping? (i) 1.0 in from the wall (ii) 1.732 m from the wall (iii) 1.0 m above the floor (iv) 1.732 m above the floor The correct answer is
(i) and (iii)
(i) and (iv)
(ii) and (iii)
(ii) and (iv)
If a body is lying on a plane whose inclination with the horizontal is less than the angle of friction, then? (i) A force is required to move the body upwards (ii) A force is required to move the body downward (iii) The body will not be in equilibrium The correct answer is
Only (i)
Only (ii)
Both (i) and (ii)
Both (i) and (iii)
The moment of inertia of a triangular section (base b, height h) about centroidal axis parallel to the base, is
b3h/12
bh3/3
bh3/36
bh3/2
The maximum frictional force which comes into play, when a body just begins to slide over the surface of a another body, is known
Sliding friction
Rolling friction
Limiting friction
None of these
The Centre of gravity of a 10 × 15 × 5 cm T-section from its bottom, is
7.5 cm
5.0 cm
8.75 cm
7.85 cm
A weight of 100 kg is supported by a string whose ends are attached to pegs A and B at the same level shown in below figure. The tension in the string is 
50 kg
75 kg
100 kg
120 kg
The C.G. of the shaded area of the below figure from the x-axis is 
a/4
3a/4
3b/10
3a/10
The instantaneous centre of a member lies at the point of intersection of two lines drawn at the ends of the member such that the lines are inclined to the direction of motion of the ends at
30°
45°
60°
90°
The angle which an inclined surface makes with the horizontal when a body placed on it is on the point of moving down, is called
Angle of repose
Angle of friction
Angle of inclination
None of these
On a ladder resting on a rough ground and leaning against a smooth vertical wall, the force of friction acts
Downwards at its upper end
Upwards at its upper end
Perpendicular to the wall at its upper end
Zero at its upper end
Centre of gravity of a thin hollow cone lies on the axis of symmetry at a height of
One-half of the total height above base
One-third of the total height above base
One-fourth of the total height above base
None of these
The rate of change of displacement of a body with respect to its surrounding, is known
Velocity
Acceleration
Speed
None of these
Newtons Law of Motion is:
Everybody continues in its state of rest or of uniform motion in a straight line, unless it is acted upon by some external force
The rate of change of momentum is directly proportional to the impressed force, and takes place in the same direction, in which the force acts
To every action, there is always an equal and opposite reaction
All the above
A shell of mass 100 kg travelling with a velocity of 10 m/sec breaks into two equal pieces during an explosion which provides an extra kinetic energy of 20000 Joules. If the pieces continue to move in the same direction as before, then the speed of the faster one must be
20 m/sec
30 m/sec
40 m/sec
50 m/sec
The shape of a suspended cable under its own weight, is
Parabolic
Circular
Catenary
Elliptical
Select the correct statement
The body centrode rolls on the space centrode
The space centrode rolls on the body centrode
Both body and space centrodes may role on each other
The body centrode never touches space centrode
To attain the synchronous orbit, the launch of a satellite, is done from a place
On equator
On 30° latitude
On 45° latitude
On the poles
For the given values of initial velocity of projection and angle of inclination of the plane, the maximum range for a projectile projected upwards will be obtained, if the angle of projection is
α = π/4 - β/2
α = π/2 + β/2
α = β/2 - π/2
α = π/4 - β/2
If two forces of 3 kg and 4 kg act at right angles to each other, their resultant force will be equal to
7 kg
1 kg
5 kg
None of these
Two shots fired simultaneously from the top and bottom of a vertical tower with elevations of 30° and 45° respectively strike a target simultaneously. If horizontal distance of the target from the tower is 1000 m, the height of the tower is
350 m
375 m
400 m
425 m
A ball is dropped from a height of 2.25 m on a smooth floor and rises to a height of 1.00 m after the bounce. The coefficient of restitution between the ball and the floor is
0.33
0.44
0.57
0.67
The equation of motion of a particle starting from rest along a straight line is x = t3 - 3t2+ 5. The ratio of the accelerations after 5 sec and 3 sec will be
2
3
4
5