Advertisements
Advertisements
рдкреНрд░рд╢реНрди
Fig 3.17 below shows a lever in use.
(a) To which class of lever does it belong?
(b) If FA = 80 cm, AB = 20 cm, find its mechanical advantage.
(c) Calculate the value of E.
Advertisements
рдЙрддреНрддрд░
(a) This is a class II lever.
(b) Given: FA=80 cm, AB = 20 cm, BF= FA+AB=100cm
Mechanical advantage M.A = `"ЁЭР╡ЁЭР╣"/"ЁЭР┤ЁЭР╣"`= `100/80` = 1.25
(c) Effort (E) = `"ЁЭР┐ЁЭСЬЁЭСОЁЭСС (ЁЭР┐)"/"ЁЭСА.ЁЭР┤"` = `5 /1.25` = 4 ЁЭР╛ЁЭСФЁЭСУ
рд╕рдВрдмрдВрдзрд┐рдд рдкреНрд░рд╢реНрди
A 4 m long rod of negligible weight is to be balanced about a point 125 cm from one end and a load of 18 kgf is suspended at a point 60 cm from the support on the shorter arm.
- If a weight W is placed at a distance of 250 cm from the support on the longer arm to balance the rod, find W.
- If a weight 5 kgf is kept to balance the rod, find its position.
- To which class of lever does it belong?
A lever of length 9 cm has its load arm 5 cm long and the effort arm is 9 cm long.
- To which class does it belong?
- Draw a diagram of the lever showing the position of fulcrum F and directions of both the load L and effort E.
- What is the mechanical advantage and velocity ratio if the efficiency is 100%?
- What will be the mechanical advantage and velocity ratio if the efficiency becomes 50%?
Which class of lever found in the human body is being used by a boy when he raises the weight of his body on his toes?
The following belong to which class of lever?
An oar of a boat
The following belong to which class of lever?
Sugar tongs
The following belong to which class of lever?
Wheelbarrow
In the diagram shown alongside a claw hammer, mark the fulcrum (F) and indicate the directions of load (L) and effort (E) with arrows. What class of lever is it? Give one more example of this class of lever.
The diagram below shows a lever in use.
(i) To which class of lever does it belong?
(ii) If FA = 40 cm, AB = 60 cm, then find the mechanical advantage of the lever.
The diagram shows the use of a lever.
- State the principle of moments as applied to the above lever.
- Which class of lever is this? Give an example of this class of lever.
- If FA = 100 cm, AB = 90 cm, calculate the minimum effort required to lift the load.
What is a first-order lever?
