# Physics

posted by .

A boat sets off perpendicular to the bank, to cross a river width of 250m. The speed of the boat in still water is 3.20ms-1, however there is a current downstream at 1.20ms-1, which puss the boat sideways.
a) Find the resultant velocity of the boat.
b) Find the total distance the boat travels in crossing the river.
c) How long does the crossing take?
d) How far downstream from the starting point does the boat travel?

• Physics -

a. add the two velocities as vectors.
find the angle of travel down stream
b. distance downstream: you have the angle, and the distance across
c. time=250m/3.20m/s
d. distance downstream=timeinwater/1.20

• Physics -

thanks. the answers to b. is 167m and the answer to d. is 93.7 m. but I'm not sure how to get that. would you please care to explain how to get that?

• Physics -

b. angle: arctan 1.2/3.2
then distance downstreem=250/cosangle
I get for the angle...0.359radians
then for distance = 250/cos.259=259m
Your answer is not possible.
Now another way: time to get across=250/3.2=78.1sec
distance downstream=78.1*1.2=93.7m
now distance total=sqrt(93.7^2+250^2) which is greater than your answer also.
your answer to b is wrong.

• Physics -

a. Vb + Vc = 3.2i + 1.2 = 3.42m/s[69.4o]
= 3.42m/s[20.6o] E. of N.

b. d = 250/Cos20.6 = 267 m.

c. d = V*t = 267 m
3.42*t = 267
t = 78.1 s.

d. d = 250*Tan20.6 = 94 m

## Respond to this Question

 First Name School Subject Your Answer

## Similar Questions

1. ### Physics

A boat is to be driven from a point on the South bank of a river which flows West-to-East to a destination on the North Bank. The destination is in a direction of N60E from the starting point. The river is 0.2 km wide. The driver of …
2. ### Physics

A boat travelling at 30km/hr relative to water is headed away from the bank of a river and downstream. The river is 1/2 km wide and flows at 6km/hr. The boat arrives at the opposite bank in 1.24 min. I calculated the perpendicular …
3. ### 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.) …
4. ### 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?
5. ### 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?
6. ### Physics

A boat crosses a river of width 113 m in which the current has a uniform speed of 0.933 m/s. The pilot maintains a bearing (i.e., the direction in which the boat points) perpendicular to the river and a throttle setting to give a constant …
7. ### Mechanics

A boat has a speed of 15ms-1 in still water. It is used to cross a river 500m wide along which there is a strong current of 0.9ms-1. The boat is being directed to the opposite bank, but is carried downstream. Calculate: a) The boat …
8. ### Science

A boat has a speed of 15ms-1 in still water. It is used to cross a river 500m wide along which there is a strong current of 0.9ms-1. The boat is being directed to the opposite bank, but is carried downstream. Calculate: a) The boat …
9. ### Physics

A boat crosses a river of width 115 m in which the current has a uniform speed of 1.84 m/s. The pilot maintains a bearing (i.e., the direction in which the boat points) perpendicular to the river and a throttle setting to give a constant …
10. ### Vectors

A boat is capable of 20 km/h in still water. You wish to cross the river downstream so that the angle the boat's push makes with the bank is 50 degrees. At what angle to the bank should the boat steer if the current is 8 km/h?

More Similar Questions