Thread: easy question

Originally Posted by Mr Rayon

When the space shuttle takes off, its initial acceleration is 3.0 m/s^2. It has an initial mass of about 2.2* 10^6 kg.

What is the magnitude of the upward thrust as it takes off?

EDIT:I tried substituting the value for the mass and the acceleration into Newton's Second Law of Motion (F=ma) but got 6.6*10^6 N. This is not the correct answer. The correct answer should be 2.9*107 N, according to my textbook. Could somebody please show me the complete working out? Perhaps I misunderstood what it meant by upward thrust?

Fnet = ma = (2.2 x 10^6)(3.0) = 6.6 x 10^6.

Fnet = Thrust - Weight force = thrust - (2.2 x 10^6)(g) = thrust - (2.2 x 10^6)(9.8) = thrust - 2.156 x 10^7.

Therefore 6.6 x 10^6 = thrust - 2.156 x 10^7.

I get thrust = 2.816 x 10^7 N, a slightly different answer to the book.