Advertisements
Advertisements
प्रश्न
उत्तर
A crowbar is a class I lever, Thus its fulcrum lies in between the load and effort
Given, load, L = 500 kgf
Lenght of crowbar = 4 m = 400cm
Therefore, load arm = 50 cm
Effort arm = 400 - 50 cm = 350 cm
Let effort = E
Now, M.A = `"effort arm"/"load arm" = 350/50` = 7
Also, M.A = `"L"/"E"`
7 = `500/"E"`
or, E = 71.4 kgf
APPEARS IN
संबंधित प्रश्न
A coolie uses a sloping wooden plank of length 2.0 m to push up a drum of mass 100 kg into the truck at a height 1.0 m.
(a) What is the mechanical advantage of the sloping plank?
(b) How much effort is needed to push the drum up into the truck?
What assumption have you made in arriving at the answer in part (b) above?
A gear system has one wheel with 10 teeth and the other wheel with 50 teeth. Calculate the gain in speed and the gain in torque that you can obtain using them. What will be the gear ration in each case?
In following figure, draw a tackle to lift the load by applying the force in the downward direction.
- Mark in the diagram the direction of load L and effort E.
- If the load is raised by 1 m, through what distance will the effort move?
- State how many strands of tackle are supporting the load?
- What is the mechanical advantage of the system?
A block and tackle system has 5 pulleys. If an effort 0f 1000 N is needed in the downward direction to raise a load of 4500 N, calculate:
- the mechanical advantage
- the velocity ratio, and
- the efficiency of the system.
A block and tackle system has the velocity ratio 3. Draw a labelled diagram of the system indicating the points of application and the directions of load L and effort E. A man can exert a pull of 200 kgf. What is the maximum load he can raise with this pulley system is its efficiency is 60%?
You are given four pulleys and three strings. Draw a neat and labelled diagram to use them so as to obtain a maximum mechanical advantage equal to 8. In you diagram make the directions of load, effort and tension in each strand. What assumptions have you made to obtain the required mechanical advantage?
A single fixed pulley and a movable pulley both are separately used to lift a load of 50 kgf to the same height. Compare the efforts applied in an ideal situation.
A machine is driven by a 50 kg mass falling at a rate of 10.0 m in 5s. It lifts n load of 250 kgf. Taking the force of gravity on 1 kg mass as 10 N. Calculate the power input to the machine. If the efficiency of the machine is 60%, find the height to which the load is raised in 5s.
The mechanical advantage of a machine is 5 and its efficiency is 80%. It is used to lift a load of 200 kgf to a height of 20 m. Calculate:
(i) The effort required, and
(ii) The work done on the machine (g = 10 ms−2).
A pulley system has a velocity ratio 3. Draw a diagram showing the point of application and direction of load (L), effort (E) and tension (T). It lifts a load of 150 N by an effort of 60 N. Calculate its mechanical advantage. Is the pulley system ideal? Give reason.
