Physics - Review Answer 29

Site hosted by Angelfire.com: Build your free website today!

Main Desktop

Lessons Desktop

Review Desktop

Lab Desktop

Chart Desktop

29.

An airplane has a velocity compared to air of 850. km/h at 90.0^o. The air has a velocity compared to ground of 120. km/h at 300.^o. What is the airplane's velocity compared to the ground.

A. 730 km/h at 90^o

B. 642 km/h at 60^o

C. 753 km/h at 82.1^o

D. 870 km/h at 90^o

v_pg = v_pa + v_ag (v_{plane to ground} = v_{plane to air} + v_{air to ground})

v_pa = 850. km/h at 90^o (It has no North/South Component)

v_ag can be broken into a North Component and a West Component

v_ag North = 120. km/h x Sin 30^o = 60.0 km/h at 360^o

v_ag West = 120. km/h x Cos 30^o = 104 km/h at 270^o

v_ag North = 60.0 km/h

v_ag East = 850. km/h - 104 km/h = 746 km/h

Now combine the components to get the resultant.

v_ag = ( (746 km/h)² + (104 km/h)² )^1/2 = 753 km/h

Heading = Tan^-1 ( (746 km/h) / (104 km/h) ) = 82.1^o

This is a heading and not just an angle because it is the clockwise angle from North.

The Correct Answer is C