Daily Physics (X)

Machine -1

1) To use the machine as a force multiplier, What type (class) of lever should be preferably be used ? draw a sketch of such a lever.

2) A pair of scissors and a pair of pliers belong to the same class of levers.

A) which one has a mechanical advantage less than 1 ?

B) state to usefulness of such a machine whose mechanical advantage is less than 1.

3) what is the mechanical advantage of liver of third order always less than one? give one example of this class of liver.

4) With the help of a simple diagram, show that mechanical advantages of a single fixed Pulley is 1 and that of a single movable pulley is 2.

5) What is meant by the term machine ? does it to do more work then input ?

6) Name for simple machines.

7)  Define mechanical advantage, velocity ratio and efficiency of a machine . How are these related to each other.

8)  How can lever of first order be distinguished from second or third order ?

9) which class of levers has a mechanical advantage always less than one. Explain briefly with a diagram why their mechanical advantage is less than one.

10) A crow bar of length 150 cm has its fulcrum at a distance of 25 cm from the load. Calculate the mechanical advantage of the crow bar.

11) A machine is driven by a100 kg mass that falls 8.0 m in 4.0s. It  lifts a load of mass 500 kg vertically upwards.

A) what is the force in Newton, exerted by the falling mass?

B) what is the work done by 100 kg mass falling through 8.0 m.

C) what is the power input to the machine?

D) If efficiency of the machine is 75%(or 0.75), what is the power output of the machine?

E)  what is the work done by the machine (in 4.0 s).

12) Define efficiency, mechanical advantage and velocity ratio for a machine. How are they related to each other?

13) How do you distinguish a lever of the first order from a second order or third order?

14) The mechanical advantage of the lever of the second class is always more than 1 and that of the third kind is always less than. Explain.

15) A machine raises a load of 1000 N through a height of 1m in 10s. Calculate its power.

16) a(Draw a labelled diagram of a block and tackle pulley system with mechanical advantage.

b)  In above case find the distance moved by effort of load rises vertically by 10m.

c) If load is 5 kg and effort is 20N,  calculate the efficiency. (g= 10m/s²)

d) State two methods by which efficiency can be increased.

e) why efficiency is likely to be different for much smaller loads?

17) a) A machine is driven by a 100 kg mass falling at the rate of 8m in 4s. It lifts a load of 500 kgf. Calculate the power input of the machine.

b) If the efficiency is 75%, to what height the load is lifted in 4s ?

18) A crow -bar of length 120cm has its fulcrum 20cm from the load. it is used to raise a load of 150 N. Calculate

A) velocity ratio.

B) effort required.

C) what type of lever is it?

19)  What class of lever is the wheel barrow? Give one more example of this class of lever

20) What is block and tackle ? Explain what is its mechanical advantage and velocity ratio?

21) Define and explain:

A) effort

B) load

C) mechanical advantage

D) velocity ratio

E) efficiency as applied to a simple machine. Give their relations

22) What type of levers are the following:

A) fishing rod

B) Scissors

C) Oar of a boat

D) sugar tongs

23) A crow -bar of length 120cm has its fulcrum situated at a distance of 20cm from the load. Calculate the mechanical advantage of the crow -bar. If load is 90N, how much is needed?

24) a) Does the weight of the single fixed pulley reduce its mechanical advantage?

b) how can a single pulley be used to reduce the force required to raise the load ?

25) Draw the diagram of pulley block and tackle and hence calculate its M. A and V. R