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प्रश्न
State two functions of a machine.
State true functions of machine.
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उत्तर
Various functions that a machine can perform are:
- Changing the direction of applied force – Example: When a flag is hoisted with the help of a pulley.
- Changing the magnitude of applied force – Example: Bottle opener multiplies the applied force and much less effort is required to open the cap.
- Applying force at a convenient point – Example: In a pair of scissors, the input force is applied at the handle of the scissors which cuts the paper at the other end of the blade.
- Changing the speed of an object – Example: While riding a bicycle, force is applied on pedals which multiplies the speed.
संबंधित प्रश्न
A block and tackle system has V.R. = 5.
Rohan exerts a pull of 150 kgf. What is the maximum load he can raise with this pulley system if its efficiency = 75%?
The pulley system has drawn lifts a load of 150 N when an effort of 60 N is applied. Find its mechanical advantage.
Is the above pulley system an ideal machine or not?
State whether the following statement is True or False.
A pulley changes the direction of force.
What is the mechanical advantage of an ideal pulley?
The mechanical advantage of an actual pulley is less than one. Give a reason. What is the justification for using the pulley then?
What is the justification for using the pulley then ?
Differentiate between a single fixed pulley and a single movable pulley.
Explain the working of a gear system.
Explain how a gear system can be used to obtain gain in torque? Given one example.
Define the following term in reference to a gear system for Gain in speed ?
What is a block and tackle system of pulleys?
Fig shown a block and tackles system of pulleys used to lift a load.
(i) How many strands of tackle are supporting the load?
(ii) Draw arrows to represent tension in each stand.
(iii) What is the mechanical advantage of the system?
(iv) When load is pulled up by a distance 1 m how far does the effort end move?
What is the relation between the mechanical advantage and the number of strands of string used to support the load, in a ‘block and tackle’ set-up?
Draw a diagram of a single fixed pulley and obtain expressions for its:
(i) Mechanical advantage,
(ii) Velocity ratio, and
(iii) Efficiency, in the ideal case.
The alongside figure shows the combination of a movable pulley P1 with a fixed pulley P2 used for lifting up a load W.
(i) State the function of the fixed pulley P2.
(ii) If the free end of the string moves through a distance x, find the distance by which the load W is raised.
(iii) Calculate the force to be applied at C to just raise the load W = 20 kgf, neglecting the weight of the pulley P1 and friction.
A man raises a load of 360 kgf using a block and tackle system of 3 pulleys. If the efficiency of the pulley system is 60%, what effort is applied by the man?
A pulley is a machine made up of a ______.
| Meera chose to use a block and tackle system of '9' pulleys instead of a single movable pulley to lift a heavy load. |
Why should she connect more number of pulleys in the upper fixed block?
