Advertisements
Advertisements
Question
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. If the effort end moves a distance 60 cm, what distance does the load move?
Solution
we know velocity ratio = `"d"_"E"/"d"_"L"`
and dE = 60 cm, velocity ratio = 3`
`d_L = d_E/("velocity ratio")`
= `60/3`
= 20 cm
APPEARS IN
RELATED QUESTIONS
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?
In a block and tackle system consisting of 3 pulleys, a load of 75 kgf is raised with an effort of 25 kgf. Find:
- the mechanical advantage,
- velocity ratio and
- efficiency.
In following figure, shows a block and tackle system of pulleys used to lift a load.
- How many strands of tackle are supporting the load?
- Draw arrows to represent tension T in each strand.
- What is the mechanical advantage of the system?
- When load is pulled up by a distance 1 m, how far does the effort end move?
- How much effort is needed to lift a load of 100 N?
- What will be it's V.R. if the weight of the movable block is doubled?
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?
In the fig draw a tackle to lit a load by applying the torce in a convinient direction. Mark the position of load and effort.
(i) If the load is raised by 1 m, Through what distance will the effort move?
(ii) State how many strands of tackle are supporting the load?
(iii) What is the mechanical advantage of the sysytem?
Class I lever can have M.A. = 1, M.A. < 1 and M.A. > 1. Explain each giving examples.
A fixed pulley is driven by a 100 kg mass falling at a rate of 8.0 m in 4.0 s. It lifts a load of 75.0 kgf. Calculate : the height to which the load is raised in 4.0 s.
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.
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.