2D Relative Motion Problem #1

A boat, whose speed in still water is 1.70 m/s, must cross a 260m –wide river and arrive at a point 110m upstream from where it starts. To do so, the pilot must head the boat at a 450 upstream angle. What is the speed of the river’s current?

smV

VVV

BW

WGBWBG

/70.1

X (m/s) Y (m/s)

VBW1.7sin45 1.7cos45

VWG 0

VBG Vsin23 Vcos23

2D Relative Motion Problem #1

smV

VVV

BW

WGBWBG

/70.1

X (m/s) Y (m/s)

VBW1.7sin45 1.7cos45

VWG 0

VBG Vsin23 Vcos2323cos45cos7.1 VsmV /51.0 23sin51.045sin7.1 WGV

smVWG /69.0

Problem #2

An airplane whose air speed is 620 km/h is supposed to fly in a straight path 35.00 north of east. But a steady 95 km/h wind is blowing from the north. In what direction should the plane head?

350

95km/h620km/h

Problem #2

An airplane whose air speed is 620 km/h is supposed to fly in a straight path 35.00 north of east. But a steady 95 km/h wind is blowing from the north. In what direction should the plane head?

hkmhkm /620

)9035sin(

/95

sin

35

02.7θ

The plane’s heading should be 42.20 north of east.