Question

(b)

Answer 1

Answer:

B. 1. The factors on which the mechanical advantage depends are the load, the effort, the distance moved by the load and the distance moved by the effort

2. The principle of a simple machine is the conversion of the direction and magnitude of a force input into one or more outputs of a either a different magnitude, or direction or both

3. A 75% efficiency of a simple machine means that the power of the frictional force is one quarter of the power of the input force

4. A lever is a simple machine that consists of a fulcrum over (or under) which a rigid beam can be  applied

5. There are three classes of lever

6. A pulley

Explanation:

B. 1. For simple machines, we have the Ideal Mechanical Advantage, IMA, given as follows;

$IMA = \dfrac{F_r}{F_e} = \dfrac{d_e}{d_r}$

Where;

$F_r$ = The resistance force (The load)

$F_e$ = The effort force

$d_e$ = The distance moved by the effort

$d_r$ = The distance the load is moved

Therefore, the factors on which the mechanical advantage depends are the load, the effort, the distance moved by the load and the distance moved by the effort

2. The principle of a simple machine is the conversion of the direction and magnitude of a force input into one or more outputs of a either a different magnitude, or direction or both

3. The mechanical efficiency of a simple machine, η, can be expressed as follows;

$\eta =\dfrac{P_{out}}{P_{in}}$

Where;

$P_{out}$ = The power at output

$P_{in}$ = The input power

$P_{in}$ = $P_{out}$ + $P_{friction}$

$P_{friction}$ = The frictional force's power

Therefore, an efficiency of 75% means that we have;

$P_{out}$ = η × $P_{in}$ = 0.75 × $P_{in}$ = 0.75·$P_{in}$

From which we have;

$P_{in}$ = $P_{out}$ + $P_{friction}$ = 0.75·$P_{in}$ + $P_{friction}$

∴  $P_{friction}$ = $P_{in}$ - 0.75·$P_{in}$ = 0.25·$P_{in}$

Therefore, 75% efficiency of a simple machine means that the power of the frictional force is 0.25 × (or one quarter of) the power of the input force

4. A lever is a simple machine that consists of a fulcrum over (or under) which a rigid beam can be  applied

5. There are three classes of lever

(a) First class lever (b) Second class lever and (c) Third class lever

6. A pulley

A pulley acts by lifting a load upward from a downward applied force.