Question

A boat of mass 225 kg drifts along a river at a speed of 21 m/s to the west. what impulse is required to decrease the speed of the boat to 15 m/s to the west?

Answer 1

Answer is below

Step-by-step explanation:

1350kg*m/s east

Answer 2

The impulse required to decrease the speed of the boat is equal to the variation of momentum of the boat:

`J=\Delta p=m \Delta v`
where
m=225 kg is the mass of the boat

`\Delta v=v_f-v_i=15 m/s-21 m/s=-6 m/s` is the variation of velocity of the boat
By substituting the numbers into the first equation, we find the impulse:

`J=m\Delta v=(225 kg)(-6 m/s)=-1350 N s`
and the negative sign means the direction of the impulse is against the direction of motion of the boat.