Ah more physics help! A reconnaissance plane flies 531 km away from its base at 944 m/s, then flies back to its base at 1416 m/s. What is its average speed? Answer in units of m/s pretty please:)

Question

anonymous · Answer

Average speed= total distance covered / elapsed time . This is an easy calculation.

anonymous · Answer

soo... 531000/ ? I don't understand how to get the elapsed time. Somehow i keep getting 566.4

anonymous · Answer

So you find the total time of the journey by v=d/t (be careful with your units make sure everything is in metres and seconds) and similarly for the flight back. You add those two times which give you total time. Total distance is just 531km(2)=1062km.

anonymous · Answer

Is it going to be 1062/(1416+944)? sorry i'm super bad at math and science

anonymous · Answer

Let's do this step by step. What's the time for the first trip?

anonymous · Answer

Well if it is 944m/s, is it going to be 944 m? Or is that supposed to be 531000/944?

anonymous · Answer

*s

anonymous · Answer

Yes so you get 562.5 seconds. What's the time for the second trip?

anonymous · Answer

375s?

anonymous · Answer

Correct. Now you have v= 2(531000m) / (375+562.5)s

anonymous · Answer

Thank you so much!

anonymous · Answer

No problem :) .

anonymous · Answer

Do you mind helping me with one more problem?

anonymous · Answer

Sure.

anonymous · Answer

ok thanks. Consider a car which is traveling along a straight road with constant acceleration a .There are two checkpoints A and B which are a distance 108 m apart. The time it takes for the car to travel from A to B is 4.07 s. What is the velocity for B in the case of the acceleration being 3.82 m/s^2

anonymous · Answer

This is a 1-Dimensional problem . We are given a distance x of 108 m which the car covers in 4.07 seconds. We first find the initial speed at A from x=v(initial)t + 1/2at^2 . Then solve for v(final) from v(final)^2=v(initial)^2 + 2ax

anonymous · Answer

Ok, just to make sure I'm doing this right, is the initial 20.2 m/s?

anonymous · Answer

or 39.2?

anonymous · Answer

Don't keep guessing , derive the formula for v(initial). What is it?

anonymous · Answer

25.50

anonymous · Answer

What is v(initial)= ? in general...?

anonymous · Answer

You mean by definition? Starting velocity/ original velocity- in this case A is initial velocity

anonymous · Answer

Sorry I'm an idiot. But I did the formula of 108=4.07x + .5(3.08)(4.07)^2

anonymous · Answer

ok. I see what I did wrong. thank you for all your help!

anonymous · Answer

Don't mention it :)