Math

posted by .

A boat, whose speed in still water is 2.80m/s , must cross a 280m wide river and arrive at a point 120m upstream from where it starts. To do so, the pilot must head the boat at a 45.0 degrees upstream angle. What is the speed of the river's current?

  • Math -

    Well, if he is going upstream, his boat velocity relative to water is 2.80cos45.

    Watervelocity-boatveloicy=ground speed

    so we need ground speed. WE know how far he went 120, but time. Well, easy. Going across the river, he went 280m with a velocity of 2.80sin45. So time in the water is 280/2.8sin45= 141 (check that) seconds

    water velocity= ground speed+boatvelocity
    water velocity= 120/141 m/s - 2.8*.707
    and you can find it from that.
    The negative means it is going opposite to the boat direction

Respond to this Question

First Name
School Subject
Your Answer

Similar Questions

  1. physics

    A boat’s speed in still water is vBW = 1.85 m/s. If the boat is to travel directly across a river whose current has speed vWS = 1.20 m/s, at what upstream angle must the boat head?
  2. physics

    You are riding in a boat whose speed relative to the water is 4.7 m/s. The boat points at an angle of 24.4° upstream on a river flowing at 13.1 m/s. Find the time it takes for the boat to reach the opposite shore if the river is 25.9 …
  3. physics

    Sheena can row a boat at 2.90 mi/h in still water. She needs to cross a river that is 1.22 mi wide with a current flowing at 1.55 mi/h. Not having her calculator ready, she guesses that to go straight across, she should head 60.0° …
  4. Physics

    A boat must cross a 260-m-wide river and arrive at a point 110 upstream from where it starts. To do so, the pilot must head the boat at a 45 degree upstream angle. THe current has speed 2.3 m/s. a) What is the speed of the boat in …
  5. physics

    You are riding in a boat whose speed relative to the water is 6.9 m/s. The boat points at an angle of 25.0° upstream on a river flowing at 15.1 m/s. Find the time it takes for the boat to reach the opposite shore if the river is 26.5 …
  6. physics

    Sheena can row a boat at 3.13 mi/h in still water. She needs to cross a river that is 1.10 mi wide with a current flowing at 1.75 mi/h. Not having her calculator ready, she guesses that to go straight across, she should head 60.0° …
  7. physics

    You are riding in a boat whose speed relative to the water is 4.5 m/s. The boat points at an angle of 25.1¡ã upstream on a river flowing at 12.8 m/s. Find the time it takes for the boat to reach the opposite shore if the river is …
  8. physics

    You are riding in a boat whose speed relative to the water is 7.4 m/s. The boat points at an angle of 24.8° upstream on a river flowing at 15.2 m/s. Find the time it takes for the boat to reach the opposite shore if the river is 26.1 …
  9. Physics

    A man which travel due north in other to cross a river 5km wide flowing due east at 3km/h. If he can roll at 10km/h in still water. Find either by scale drawing or by calculation (1) the direction in which he must head is boat in order …
  10. physics

    A boater wants to head straight across a river that has a current of 3 km/hr. If the top speed of the boat in still water is 4 km/hr. 1.find the direction the boat must travel into the current to go straight across the river?

More Similar Questions