Final answer:
The reading on the spring balance when a lift accelerates upwards with a 1 kg mass will be 12.3 newtons, due to the combination of gravitational force and the lift's upward force.
Step-by-step explanation:
The reading on a spring balance, when it is accelerating upwards with a mass of 1 kg hanging at its end, can be found by applying Newton's second law of motion. The total force on the mass is the sum of the gravitational force and the force due to the acceleration of the lift.
To calculate the force, we use:
F = m × (g + a)
where m is the mass (1 kg), g is the acceleration due to gravity (9.8 m/s²), and a is the acceleration of the lift (2.5 m/s²).
Thus, the force F = 1 kg × (9.8 m/s² + 2.5 m/s²) = 1 kg × 12.3 m/s² = 12.3 N.
The reading on the spring balance will be 12.3 newtons, showing the increased apparent weight due to the upward acceleration.