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I am not sure why this is not clicking...

An object hangs from a spring balance. The balance registers 30 N in the air and when it is immersed in water it reads 20 N. What is the buoyant force on this object? Draw a FBD to solve this.

FBD

[tex]\uparrow F_b[/tex]

OBJECT

[tex]\downarrow F_W[/tex]

Do I need to take into account any other forces?

It is multiple choice a) 20 N up

b) 10 N up

c) 10 N down

d) 20 N down

I am pretty sure it is not c or d......as that wouldn't seem like a "buoyant" force But I am not sure how to set up my Newton's 2nd equation?

Is it just [tex]\sum F=F_{weight}-F_{buoyant}=20[/tex]

so F_buoyant=10N?

It just seems strange that we spent all day taking atmospheric pressure into account, but now we do not...

An object hangs from a spring balance. The balance registers 30 N in the air and when it is immersed in water it reads 20 N. What is the buoyant force on this object? Draw a FBD to solve this.

FBD

[tex]\uparrow F_b[/tex]

OBJECT

[tex]\downarrow F_W[/tex]

Do I need to take into account any other forces?

It is multiple choice a) 20 N up

b) 10 N up

c) 10 N down

d) 20 N down

I am pretty sure it is not c or d......as that wouldn't seem like a "buoyant" force But I am not sure how to set up my Newton's 2nd equation?

Is it just [tex]\sum F=F_{weight}-F_{buoyant}=20[/tex]

so F_buoyant=10N?

It just seems strange that we spent all day taking atmospheric pressure into account, but now we do not...

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