Calculating Force to Submerge 5 kg Object in Water

[physgrl]

Homework Statement

A 5-kg object displaces 10 kg of water. What is the force required to submerge the object?

a. 24 N

b. 147 N

c. 98 N

*d. 49 N

Homework Equations

Buoyant Force = Weight of the Water displaced

The Attempt at a Solution

Weight of the Water displaced=10kg*9.81m/s^2=98.1N

If the buoyant force is 98.1N an equal or greater force must be applied to submerge the object.

The answer key says its 49N...why?

 

[LawrenceC]

You are forgetting about the weight of the object. If you draw a free body diagram and apply all the forces, it becomes obvious.

 

[physgrl]

Ohh right the object pushed downward too