Question

A juniper-wood plank measuring 0.31 ft by 1 ft by 17 ft is totally submerged in water.

(a) What is its weight?

(b) What is the buoyant force acting on it?

(c) What is the size and the direction of the net force on it?

size

direction

Answer 1

PART (a):

Volume of the wooden plank is given by:

Density of the plank, D = 35 lb/ft³

Therefore, It's weight is given by:

>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

PART (b):

We have, Density of water, D_w = 62.4 lb/ft³

Buoyant force acting on it is given by:

>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

PART (c):

Net force = Buoyant force - weight

Direction : Upwards

(Because, Buoyant force (acting upwards) is greater than it's weight which is directed downwards.)