When a person stands on a weighing scale, the reading on the scale corresponds to the normal force exerted by the person on the scale. In this case, we need to determine the reading on the weighing scale when the lift is ascending upwards with a uniform acceleration of 9 m/s^2.


- Weight of the person = mg, where m is the mass of the person and g is the acceleration due to gravity.
- Normal force exerted by the person on the weighing scale = N.


When the lift is at rest or moving with a constant velocity, the acceleration of the lift is zero, and the normal force exerted by the person on the weighing scale is equal to the weight of the person. However, when the lift is accelerating upwards, the net force acting on the person is the difference between the weight of the person and the normal force.

Let's calculate the net force on the person when the lift is accelerating upwards:

Net force = Weight of the person - Normal force
Net force = mg - N

According to Newton's second law, the net force on an object is equal to the mass of the object multiplied by its acceleration:

Net force = ma

Substituting the values, we have:

mg - N = ma

Solving for N, we get:

N = mg - ma


Given:
Mass of the person (m) = 50 kg
Acceleration due to gravity (g) = 10 m/s^2
Uniform acceleration of the lift (a) = 9 m/s^2

Substituting the values, we have:

N = (50 kg)(10 m/s^2) - (50 kg)(9 m/s^2)
N = 500 kg·m/s^2 - 450 kg·m/s^2
N = 50 kg·m/s^2


The reading on the weighing scale is equal to the normal force exerted by the person on the scale. From the calculation above, we found that N = 50 kg·m/s^2. However, the reading on the scale is usually given in terms of mass rather than force. Therefore, we need to convert the normal force to mass.

The weight of an object is given by the formula:

Weight = mass × acceleration due to gravity

Therefore, the mass corresponding to the normal force can be calculated as:

Mass = N / g

Substituting the values, we have:

Mass = (50 kg·m/s^2) / (10 m/s^2)
Mass = 5 kg

Therefore, the reading on the weighing scale is 5 kg, which is equivalent to 50 kg.

The correct answer is option 'C', 95 kg.