# 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? How long will it take to cross if the river is 1.7 km/h?

1. A. Vr = Vb + Vc.
20[50o] = Vb - 8i,
Vb = 20[50]+8i,
Vb = 20*Cos50+20*sin50 + 8i,
Vb = 12.9 + 15.3i + 8i = 12.9 + 23.3i.

Tan A = Y/X =23.3/12.9 = 1.80620,
A = 61o.

posted by Henry
2. Your last question doesn't make sense.

posted by Henry
3. 1.7 km wide.

Srry

posted by John
4. B. sin50 = 1.7/d. d = 2.22 km.

posted by Henry
5. 50o W. of N. = 140o CCW.

Vr = Vb + Vc.
20[140] = Vb + (-8i),
Vb = 20[140] + 8i,
Vb = 20*Cos140+20*sin140 + 8i.
Vb = -15.3 + 12.9i + 8i = -15.3 + 20.9i

Tan A = Y/X = 20.9/(-15.3) = -1.36601. A = -53.8o = 53.8o N. of W. = 126.2o CCW = 36.2O W of N.

posted by Henry

## Similar Questions

1. ### 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
2. ### 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
3. ### Physics

A boat travels at 3.8 m/s and heads straight across a river 240m wide at an angle of 145'. The river flows at 1.6 m/s. a. What is the boat's resultant speed with respect to the river bank? b. How long does ti take the boat to
4. ### Physics

A boat travels at 3.8 m/s and heads straight across a river 240m wide at an angle of 145'. The river flows at 1.6 m/s. a. What is the boat's resultant speed with respect to the river bank? b. How long does ti take the boat to
5. ### physics - need help right now.

A boat travels at 3.8 m/s and heads straight across a river 240m wide at an angle of 145'. The river flows at 1.6 m/s. a. What is the boat's resultant speed with respect to the river bank? b. How long does ti take the boat to
6. ### Physics

A boat travels at 3.8 m/s and heads straight across a river 240m wide at an angle of 145'. The river flows at 1.6 m/s. a. What is the boat's resultant speed with respect to the river bank? b. How long does ti take the boat to
7. ### 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
8. ### Physics - URGENT

A boat travels at 3.8 m/s and heads straight across a river 240m wide at an angle of 145'. The river flows at 1.6 m/s. a. What is the boat's resultant speed with respect to the river bank? b. How long does ti take the boat to
9. ### Physics

A boat travelling at 30km/h 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/h. The boat arrives at the opposite bank in 1.25min. Calculate the component of the
10. ### Physics

A boat travelling at 30km/h 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/h. The boat arrives at the opposite bank in 1.25min. Calculate the component of the

More Similar Questions