A weather research balloon of total mass 4500 kg accelerates vertically upwards from the surface of the Earth at 0.85 m s-2. Taking the acceleration due to gravity g g\,g as 9.81 m s-2, what is the upward lift force acting on the balloon?
3.8×103 N3.8 \times 10^{3}\text{ N}3.8×103 N
4.1×104 N4.1 \times 10^{4}\text{ N}4.1×104 N
4.4×104 N4.4 \times 10^{4}\text{ N}4.4×104 N
4.8×104 N4.8 \times 10^{4}\text{ N}4.8×104 N
