A man weighs 80kg. He stands on a weighing scale in a lift which is moving upwards with a uniform acceleration of 5m / s² . What would be the reading on the scale.(g= 10 m/s²0)

To find the reading on the weighing scale, we need to determine the normal force (apparent weight) acting on the man inside the accelerating lift.

Let us first list the given parameters:
Mass of the man, $m=80\text{kg}$
Acceleration of the lift upwards, $a=5{\text{m/s}}^2$
Acceleration due to gravity, $g=10{\text{m/s}}^2$

When a person stands on a weighing scale in a lift, the scale measures the normal reaction force ($N$) exerted by the scale on the person.

According to Newton's second law of motion, when the lift moves upwards with an acceleration $a$, the net force acting on the man is directed upwards:
$F_{\text{net}}=m·a$

The forces acting on the man are:
1. The normal force ($N$) acting vertically upwards.
2. The gravitational force ($W=m·g$) acting vertically downwards.

Setting up the equation of motion:
$N-m·g=m·a$

Solving for the normal force $N$:
$N=m·(g+a)$

Substituting the given values into the equation:
$N=80·(10+5)$
$N=80·15$
$N=1200\text{N}$

Therefore, the reading on the scale is 1200 N.