Question

A man uses a crowbar of length 1.5m to raise a load of 75 kgf by putting a sharp edge below the bar at a distance of 1m from his hand. The load is at the opposite end of the effort. Calculate (i) load arm (ii) effort arm (iii) mechanical advantage and (iv) the effort needed.

• A. Load arm = 0.5 m Effort arm = 1 m M.A = 2 Effort = 37.9 kgf
• B. Load arm = 0.5 m Effort arm = 1 m M.A = 2 Effort = 37.5 kgf
• C. Load arm = 0.5 m Effort arm = 5 m M.A = 2 Effort = 37.9 kgf
• D. Load arm = 0.5 m Effort arm = 1 m M.A = 2 Effort = 59 Kgf

Answer 1

The correct option is B

Load arm = 0.5 m

Effort arm = 1 m

M.A = 2

Effort = 37.5 kgf

Here,

Load = 75 kgf

Load arm = 0.5 m

Effort arm = 1

$MA=$ $\frac{effortarm}{loadarm}=\frac{1}{0.5}=2$
$Effortneeded=$ $\frac{load}{M.A}=\frac{75}{2}=37.5$