An aircraft has an initial mass of m0 and an initial acceleration of a0. After flying for 2 hours, the mass of the aircraft has decreased by 11%, due to the burning of the fuel. If the propulsive force provided by the engines is constant, what is the expression for the new acceleration, a2, at this time? You may assume that the aircraft is in level flight at all times and the air resistance is negligible.

Question

Select one:
a. a2=0.89a0
b. a2=a0/0.89
c. a2=1.11a0
d. a2=1+0.11a0

Answer 1

Using Newton's second law: F=ma
and since F=constant,
we have
m0a0=m2a2
Knowing that m2/m0=(1-0.11)=0.89
you can solve for a2.

Note: it does not seem realistic that an aircraft accelerates horizontally for two hours and continue accelerating!