A student of mass 75kg stands in a lift, what is the normal reaction force(upward force) on him when the lift is accelerating:
a). Upwards at 0.65m/s^2 ?
b). Downwards at 0.65m/s^2 ?
(600,750,900,150)n
Its very hard
To determine the normal reaction force on the student, we need to consider the forces acting on the student in the lift.
a) When the lift is accelerating upwards at 0.65 m/s^2:
In this case, the net force acting on the student is the difference between the force of gravity and the force due to acceleration.
The force due to gravity can be calculated using the gravitational force equation:
Force of gravity = mass × acceleration due to gravity
Given that the mass of the student is 75 kg and the acceleration due to gravity is approximately 9.8 m/s^2, the force of gravity is:
Force of gravity = 75 kg × 9.8 m/s^2 = 735 N (downwards)
The force due to acceleration can be calculated using Newton's second law of motion:
Force due to acceleration = mass × acceleration
Given that the mass of the student is 75 kg and the acceleration of the lift is 0.65 m/s^2 (upwards), the force due to acceleration is:
Force due to acceleration = 75 kg × 0.65 m/s^2 = 48.75 N (upwards)
To find the normal reaction force, we sum up the forces acting on the student:
Normal reaction force = Force of gravity + Force due to acceleration
Normal reaction force = 735 N (downwards) + 48.75 N (upwards)
Normal reaction force = 686.25 N (downwards)
Therefore, the normal reaction force on the student when the lift is accelerating upwards at 0.65 m/s^2 is 686.25 N (downwards).
b) When the lift is accelerating downwards at 0.65 m/s^2:
In this case, the net force acting on the student is the sum of the force of gravity and the force due to acceleration.
Using the same calculations as before, we find that the force of gravity is 735 N (downwards).
The force due to acceleration is:
Force due to acceleration = 75 kg × (-0.65 m/s^2) = -48.75 N (downwards)
To find the normal reaction force, sum up the forces acting on the student:
Normal reaction force = Force of gravity + Force due to acceleration
Normal reaction force = 735 N (downwards) + (-48.75 N) (downwards)
Normal reaction force = 686.25 N (downwards)
Therefore, the normal reaction force on the student when the lift is accelerating downwards at 0.65 m/s^2 is 686.25 N (downwards).