Mechanical Advantage

Q.

The importance of Newton's first law of motion is that:

1. it defines acceleration

2. it defines inertia

3. it mentions force

4. it defines momentum

Q. An object is dropped from rest at a height of $150m$ and simultaneously another object is dropped from rest at a height of $100m$. What is the difference in their heights after $2s$ if both the objects drop under the same acceleration? How does the difference in heights vary with time?

Q. A spring is compressed against a rigid wall. Draw a neat and labelled diagram showing the forces acting on the spring.

Q.

A body is at rest. It may possess

1. energy

2. momentum

3. speed

4. velocity

Q. A small stone and a heavy brick are dropped from the roof of an appartment at the same time. Assume no air resistance on the bodies, which one of them will reach the ground first ?

1. Small stone
2. Heavy brick
3. Both at same time
4. Insufficient information

Q.

Aryan drops a ball from a hot air balloon flying at a height of 75 m. If the balloon is moving upwards with uniform velocity of 10 m/s, find the height of the balloon when the ball hits the ground. Take ($g=10m{s}^{-2}$ )

Q. Name the S.I. unit of force and define it?

Q. Name the SI and C.G.S units of force. How are they related?

Q. The tension (T) in the string is (Assume pulley and strings are light and smooth. Take g as acceleration due to gravity)

1. $(m_1+m_2)g$
2. $m_{2}g$
3. $\sum F=ma$
4. $m_{1}g$

Q.

The height at which the acceleration due to gravity becomes $\frac{g}{9}$, is

1. $2R$

2. $\frac{R}{\sqrt{2}}$

3. $\frac{R}{2}$

4. $\sqrt{2}R$

Q. Choose the incorrect statement among the following:-

1. The action and reaction forces act in opposite directions.
2. The action and reaction forces act on the same object.
3. The action and reaction forces always exist in pair.
4. The action and reaction forces are equal in magnitude.

Q.

Calculate the mechanical advantage of a lever when load arm = $15cm$ and effort arm = $30cm$.

Q.

Calculate the load, which can be overcome by an ideal machine, when effort = 100 N, effort arm = 60 cm, and load arm = 15 cm

Q.

Write down the units and dimensional formulae of following physical quantities:
$Impulse=force\times time$

Q. An object is dropped from rest at a height of $150m$ and simultaneously another object is dropped from rest at a height of $100m$. What is the difference in their heights after $2s$ if both the objects drop under the same acceleration? How does the difference in heights vary with time?

Q. Newton's First Law can be seen to be the special case in the Second Law

1. False
2. True

Q. An effort of 21 Kgf is applied on a machine for the movement of a load of 120 Kgf. Find the mechanical advantage of the machine.

Q.

Calculate the mechanical advantage of a lever when effort = 5 kg wt and load = 45 kg wt

Q.

Why the handle of an ordinary water handpump made longer?

1. The mechanical advantage increases with the increase in effort arm.

2. The mechanical advantage decreases with the increase in effort arm.

3. No change in mechanical advantage.

4. It will increase the efficiency.

Q. When a body starts falling down from a height 'h', its velocity after time 't' will be $v=-g.t$

1. True
2. False

Q. An officer needs to jump from the top of the wall to the ground as a training exercise. If his speed on reaching the ground is 12 m/s, what is the height of the wall? [Take: g = $10m/s^2$]

1. 3.6 m
2. 2.68 m
3. 7.2 m
4. 51.84 m

Q.

Calculate the load, which can be overcome by an ideal machine, when effort = 50 N, effort arm = 1 m and load arm = 10 cm

Q. Strings and pulleys shown in the system are ideal. Tension in the string 1 connected to ground is [g = 10 m/s²]

निकाय में दर्शायी गयी डोरियाँ तथा घिरनियाँ आदर्श हैं। धरातल से संयोजित डोरी 1 में तनाव है [g = 10 m/s²]

1. 100 N
2. 50 N
3. 150 N
4. 200 N

Q. Recoiling of a gun can be explained with the help of:

1. Newton’s First Law
2. Newton’s Second Law
3. Newton’s Third Law
4. Newton’s Law of Gravitation

Q. Water sprinkler used for grass lawns begins to rotate as soon as the water is supplied. Explain the principle on which it works.

Q. Explain the term ‘pitch’ of a screw gauge. How is it determined?

Q. What is the SI unit of force?

1. pascal
2. joule
3. ampere
4. newton

Q. Action and reaction forces act on different bodies.

1. True
2. False

Q.

The acceleration due to gravity at a height $h$ from the surface of the earth is 96% less than its value on the surface then $h$= ………… R, where R is the radius of the earth.

1. $1$

2. $2$

3. $3$

4. $4$

Q.

Write down the units and dimensional formulae of following physical quantities:
$Force=mass\times acceleration$