# Force of Friction on Boat w/ Thrust

## Homework Statement

A boat moves across the water at a constant 30 mph towards the west. If the motor is generating a thrust of 500 M then the force of friction on the boat must be...
a. 500 N to the east
b. 500 N to the west
c. less than 500 N to the east
d. less than 500 N to the west

## The Attempt at a Solution

I originally thought c, becuase the Ff must be going in the opposite direction of the boat, which would be east, and in order for it to actually be moving, Ff must be less than the thrust of 500 N, pushing the boat to the west.
C is incorrect though, so now I'm not sure what to think.

haruspex
Homework Helper
Gold Member
2020 Award

## Homework Statement

A boat moves across the water at a constant 30 mph towards the west. If the motor is generating a thrust of 500 M then the force of friction on the boat must be...
a. 500 N to the east
b. 500 N to the west
c. less than 500 N to the east
d. less than 500 N to the west

## The Attempt at a Solution

I originally thought c, becuase the Ff must be going in the opposite direction of the boat, which would be east, and in order for it to actually be moving, Ff must be less than the thrust of 500 N, pushing the boat to the west.
C is incorrect though, so now I'm not sure what to think.
You don't list any relevant equations. You must know one relating force, mass and acceleration.

You don't list any relevant equations. You must know one relating force, mass and acceleration.
Fnet = ma but the question doesn't give me mass or acceleration

haruspex
Homework Helper
Gold Member
2020 Award
Fnet = ma but the question doesn't give me mass or acceleration
It does tell you the acceleration. Read it carefully.

It does tell you the acceleration. Read it carefully.
a = 0
so Fnet = m(0) = 0
so the answer is a (500 N to the east), because Ff will be equal to the 500 N west

haruspex
Homework Helper
Gold Member
2020 Award
a = 0
so Fnet = m(0) = 0
so the answer is a (500 N to the east), because Ff will be equal to the 500 N west
Yes.

Yes.
Thank you!