Effort

Q.

What is the efficiency of a machine.

Q.

Define efficiency.

Q.

A fire tongs has its arms 20 cm long. It is used to lift a coal of weight 1.5 kgf by applying an effort at a distance of 15 cm from the fulcrum. Find : (i) the mechanical advantage of the fire tongs , and (ii) the effort needed.

1. M. A = 0.45

   Effort = 2 Kgf

2. M. A = 0.75

   Effort = 2 Kgf

3. M. A = 0.45

   Effort = 9 Kgf

4. M. A = 0.45

   Effort = 6 Kgf

Q.

The figure below shows a lever in use.

(a) To which class of lever does it belong?

(b) If AB = 1m, AF = 0.4 m, find its mechanical advantage.

(c) Calculate the value of E.

1. Class I lever, M.A = 4, Effort = 6 kgf

2. Class I lever, M.A = 4, Effort = 4 kgf

3. Class III lever, M.A = 4, Effort = 4 kgf

4. Class I lever, M.A = 1.5, Effort = 10 kgf

Q.

“A machine is 60% efficient”. What do you understand by this statement?

Q. The efficiency of a machine is 90%. If $100J$ of work is done by the effort, how much work is obtained at the load of the machine?

1. $50J$
2. $100J$
3. $90J$
4. $60J$

Q.

An effort of 50 kgf is applied at the end of a lever of the second order which supports a load of 750 kgf. Find the mechanical advantage?

Q.

A machine that has a mechanical Advantage of 9 is used for a load of 765 Kgf. Find the required effort.

1. 50 kgf

2. 90 kgf

3. 20 kgf

4. 85kgf

Q.

A man uses a crowbar of length 1.5m to raise a load of 75 kgf by putting a sharp edge below the bar at a distance of 1m from his hand. The load is at the opposite end of the effort. Calculate (i) load arm (ii) effort arm (iii) mechanical advantage and (iv) the effort needed.

1. Load arm = 0.5 m

   Effort arm = 1 m

   M.A = 2

   Effort = 37.5 kgf

2. Load arm = 0.5 m

   Effort arm = 5 m

   M.A = 2

   Effort = 37.9 kgf

3. Load arm = 0.5 m

   Effort arm = 1 m

   M.A = 2

   Effort = 59 Kgf

4. Load arm = 0.5 m

   Effort arm = 1 m

   M.A = 2

   Effort = 37.9 kgf

Q.

The given figure shows a block and tackle system of pulleys used to lift a load. When the load is pulled up by a distance 1 m, how far does the effort end move?

1. 8m

2. 2m

3. 1m

4. 4m

Q. Figure shows the use of a lever. If $FA=10cm,AB=500cm$, $load=\text{5 kgf}$, the minimum effort required to lift the load is :

1. $2500N$
2. $3550N$
3. $2520N$
4. $2550N$

Q. A man uses a crowbar of length $1.5m$ to raise a load of $75kgf$ by putting a sharp edge below the bar at a distance $1m$ from his hand. Calculate the mechanical advantage.

1. $2$
2. $0$
3. $4$
4. $1$

Q. If a machine only requires 100 N of effort to lift a load of 150 N, what is the mechanical advantage of the machine?

1. 2.5
2. 2
3. 1.5
4. 1

Q. Calculate the effort in newtons required to raise 1000 kg anchor on boat with a wheel and axle of radii 50 cm and 10 cm respectively.

1. 1000
2. 1500
3. 3000
4. 2000

Q.

A machine has a mechanical advantage of $10$. It used to lift a load of $200kgf$. Find the required effort.

1. $60kgf$

2. $90kgf$

3. $30kgf$

4. $20kgf$

Q.

A force multiplier is a simple machine that multiplies the ___.

1. speed

2. effort

3. load

4. work

Q.

A force multiplier is a simple machine that multiplies the ___.

1. speed

2. load

3. work

4. effort

Q.

When the effort arm is greater than the load arm the mechanical advantage is one.

1. True

2. False

Q. A 5 N force displaces an object by 8 m. The work done by the force is:

1. 20 J
2. 50 J
3. 40 J
4. 30 J

Q. An effort is the force applied to move or lift the load.

1. True
2. False