physics

posted by .

A boat takes 4 min. to cross a river 90m wide directly when there is no current & 5min. When there is current. find the velocity of the current.

  • physics -

    With no river flow, the boat crosses the river at 90/4 = 22.5 meters/min.
    With river flow, it's speed relative to water is the same as above, but it crosses at a speed of 90/5 = 18 m/min, relative to and perpendicular to the shore.
    Consider the vector right triangle with sides of river speed, speed relative to shore, and speed relative to water.
    If v is the river speed,
    v^2 + 18^2 = 22.5^2
    Solve for v.

Respond to this Question

First Name
School Subject
Your Answer

Similar Questions

  1. physics

    your boat departs from the bank of a river that has a swift current parallel to its banks. if you want to cross the river in the shortest amount of time, you should direct your boat a.) perpendicular to the current b.) upstream c.) …
  2. Precalc

    A boat that travels at 16 knots in calm water is sailing across a current of 3 knots on a river 250 m wide. The boat makes an angle of 35 degrees with the current heading into the current. Find the resultant velocity of the boat. How …
  3. Calculus

    A boat crosses a river and arrives at a point on the opposite bank directly across from its starting position. The boat travels at 4 m/s and the current is 2m/s. If the river is 600 m wide in what direction must the boat steer and …
  4. CALC urgent please

    A boat crosses a river and arrives at a point on the opposite bank directly across from its starting position. The boat travels at 4 m/s and the current is 2m/s. If the river is 600 m wide in what direction must the boat steer and …
  5. math

    a boat crosses a river and arrives at a point on the opposite bank directly across from its starting position. The boat traveks at 4m/s and the current is 2m/s. If the river is 600 m wide in what direction must the boat steer and how …
  6. science

    A boat crossing a .2 mile wide river is heading perpendicularly relative to shore. Its speed in still water is 4mph and the speed of the current is 6mp. a.) How far downstream will the boat land?
  7. physics

    A boat heads directly across a river 39 m wide at 3.9 m/s. The current is flowing downstream at 2.4 m/s. (a) What is the resultant velocity of the boat?
  8. physics

    A child in danger of drowning in a river is being carried downstream by a current that has a speed of 2.10 km/h. The child is 0.600 km from shore and 0.800 km upstream of a boat landing when a rescue boat sets out. (a) If the boat …
  9. Physics 111

    A boat is crossing a river. The velocity of the boat relative to the water is 4.0 m/s directed perpendicular to the river's current. The velocity of the current relative to the shore is 2.0 m/s. How long will it take for the boat to …
  10. Physics

    A person can directly cross a river of width 100 m in 4 minutes when there is no current, but it takes 5 minutes when there is current. What is the velocity of the current?

More Similar Questions