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# Help with physics

Registered User Posts: 193 Junior Member
edited September 2007
1. Kyle is flying a plane due north at 225 km/h as a wind carries it due east at 55 km/h. Find the magnitude and direction of the plane's resultant velocity and analytically.

2. Sue and Jenny kick a soccer ball at exactly the same time. Sue's foot exerts a force of 66 N north. Jenny's foot exerts a force of 88 N east. What is the magnitude and direction of the resultant force on the ball?

3. Kym is in a boat traveling 3.8 m/s straight across a river 240 m wide. The river is flowing at 1.6 m/s.
a. What is Kym's resultant velocity?
b. How long does it take Ky to cross the river?
c. How far is Kym downstream when she reaches the other side?
Post edited by grantedin on

## Replies to: Help with physics

• Registered User Posts: 513 Member
1. Again, it's just addition of velocities aka tip-to-tail if you drew them out. Resultant is a hypotenuse again, so it's just sqrt(225^2+55^2) for the magnitude, and arctan(225/55) northeast for the direction. For direction, it's always arctan(y/x)
• Registered User Posts: 513 Member
2. Forces are vectors, so use the same procedures to get the answer as in #1
• Registered User Posts: 513 Member
3. (a)Again, sqrt(3.8^2+1.6^2)
• Registered User Posts: 513 Member
(b)240/3.8, as the river will have no effect on the vertical distance she travels, only the horizontal distance
• Registered User Posts: 513 Member
(c) Use the answer you got in b and multiply that by 1.6
• Registered User Posts: 193 Junior Member
Thank you so very much!!! It is so thoughtful of you to take the time to type and explain it to me!!! Thanks a million!!!
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