A Lufthansa A320 accelerates from rest to liftoff speed of 72.8 m/s in 28.3 s. Each of the plane's two jet engines provides a forward force (thrust) of 111 kN.
(a) What is the mass of the plane?
kg
(b) How far does it travel down the runway before liftoff?
m
part a I got 1.1326e4 kg and part b is 1030.1m. part I solved mult times and all of the solutions I got are wrong, but part b is correct. any ideas on how to find the mass of the engine? thanks!
2007-10-12 01:31:19 · 2 answers · asked by Anonymous in Science & Mathematics ➔ Physics
acceleration = velocity change/time
mass = force/acceleration (remember F = MA?)
Also, some common sense: A large plane like an A320 would have to be heavier than 11,000 kg. Think at least 125 passengers at 75 kg each; how much does that leave for plane, fuel, etc.?
I think you divided 111000 by 9.8 to get 11326 kg. If so, that suggests desperation, since the total force is 2*111000 and g doesn't enter into this problem at all. I suggest you get tutoring in the interpretation of word problems and planning of solutions, at least.
2007-10-12 02:10:16 · answer #1 · answered by kirchwey 7 · 0⤊ 0⤋
You should get yourself a physics textbook - no need to buy one, your library should have a few.
In that book, you'll find extensive discussion about mass, velocity, and acceleration. You'll also find examples of questions similar to the ones you are posing here. From these, you should be able to derive the formulas that will help you resolve your questions. The book might even offer some formulas for you to try.
These are terrific questions! You really do have the mind of a physicist. Keep on thinking, asking, pushing, and you might be our next Nobel laureate in the field!
Good luck!
2007-10-12 01:43:32 · answer #2 · answered by ? 6 · 0⤊ 0⤋