If the tension in the cable supporting an elevator is equal to the weight of the elevator, the elevator may _______.

1

(a)

going up with uniform speed

(b)

going down with non-uniform speed

(c)

going up with increasing speed

(d)

going down with increasing speed

The dimension of Impulse is _______.

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(a)

MLT^-2

(b)

MLT^-1

(c)

MLT^-3

(d)

MLT

A block of mass M is pulled along a horizontal frictionless surface by a rope of mass m. Force P is applied at one end of the rope. The force which the rope exerts on the block is: _______.

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(a)

\({P\over M-m}\)

(b)

\({PM\over m+M}\)

(c)

\({P\over M(m+M)}\)

(d)

\({Pm\over M-m}\)

Action and reaction _______.

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(a)

act on two different objects

(b)

have equal magnitude

(c)

have opposite directions

(d)

all are correct

A force of 200 N is required to push a car of mass 500 kg slowly at constant speed on a level road. If a force of 500 N is applied, the acceleration of the car (in m S^-2) will be_______.

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(a)

zero

(b)

0.2

(c)

0.6

(d)

1.0.

The distance travelled by a moving body is directly proportional to time. Is any external force acting on it ?

1

(a)

When S\(\propto \) t, so acceleration = 0, Therefore, no external force is acting on the body.

A force of 36 dyne is inclined to the horizontal at an angle of 60\(^0\) . Find the acceleration in a mass of 18 g that moves in a horizontal diraction.

1

(a)

Given, F = 36 dyne at an angle of 60\(^0\) .
\(\therefore \)   Component of force along x-direction
F_x = F cos 60\(^0\) = 36 x\(\frac { 1 }{ 2 } \) = 18 dyne
 But  F_x = ma_x ,
a_x = \(\frac { { F }_{ x } }{ m } \) = \(\frac { 18 }{ 18 } \) = 1 cm/s²

If force is acting on a moving body perpendicular to the direction of motion, then what will be its effect on the speed and direction of the body ?

1

(a)

No change in speed, but change in direction is possible. Forces acting on a body in circular motion is an example.

An impulse is applied to a moving object with a force at an angle of 20\(^0\) w.r.t. velocity vector. what is the angle between the impulse vector and change in momentum vector ?

1

(a)

Impulse and change in momentum are along the same direction. Therefore, angle between these two vectors is zero degree.

Why is static friction called a self-adjusting force?

1

(a)

As the applied force increases, the static friction also increases and becomes equal to the applied force to make the object stationery. That is why static friction is called a self-adjusting force.