A block of concrete, mass 100kg, lies on a 2m long plank of wood at d= 0.5 from one end.

If a builder lifts up the other end of the plank, how much force must he apply to lift the block?

A) 125 N

B) 12.5 N

C) 250 N

D) 25N

E) 2.5 N

A block of concrete, mass 100kg, lies on a 2m long plank of wood at d= 0.5 from one end.

If a builder lifts up the other end of the plank, how much force must he apply to lift the block?

A) 125 N

B) 12.5 N

C) 250 N

D) 25N

E) 2.5 N

2 Likes

hello!

could you tell me the answer? thanks!

The answer is C 250 N

calculate the weight of the block to see the gravitational force on it:

W = 100 kg * 9.81 m/s² (standard gravitational acceleration)

the distance is given as d=0.5m

calculate the toruqe which is

distance* force

981N*0.5m= 450.5N

to uplift the block the builder should apply force by the end of the plank

Force builder= torque/ distance

450.5/2meters= 245 N

you can approximate it into 250

most probably if you use grav as 10 m/s2 you will get around 250

hope this helps