Not sure how to start this one any hints would be most helpful

[dstahn]

The cable of a 2017-kg elevator has broken, and the elevator is moving downward at a steady speed of 1.64 m/s. A safety braking system that works on friction prevents the downward speed from increasing. At what rate is the braking system converting mechanical energy to thermal energy?

Im not real sure what equations to use. Sorry I'm not very helpful. This one just kinda stopped me in my tracks for some reason.

 

[rl.bhat]

Since elevator is falling with constant velocity, the frictional force must be equal to...?
Then rate of doing work = Fr*v.
Now what is relation between the mechanical energy and the thermal energy?

 

[tomcue]

I would first start by clearly defining the problem and identifying the known variables. In this case, we know the mass of the elevator (2017 kg), its downward speed (1.64 m/s), and the fact that the safety braking system is preventing the speed from increasing.

Next, I would use the principle of conservation of energy to solve the problem. The total energy of the system (elevator + braking system) must remain constant, so the energy converted from mechanical energy to thermal energy by the braking system must be equal to the decrease in mechanical energy of the elevator.

To calculate the mechanical energy of the elevator, we can use the formula E = mgh, where m is the mass of the elevator, g is the acceleration due to gravity (9.8 m/s^2), and h is the height the elevator has descended. Since the elevator is moving at a constant speed, we can use the formula v = d/t to calculate the height h, where d is the distance the elevator has descended and t is the time it took.

Using the given speed of 1.64 m/s and the fact that the elevator has been descending for some time, we can calculate the distance it has descended. Then, using the mass of the elevator, we can calculate the mechanical energy of the system.

To find the rate at which the braking system is converting mechanical energy to thermal energy, we can use the formula P = E/t, where P is the power (rate) at which energy is being converted, E is the mechanical energy calculated previously, and t is the time it took for the elevator to descend. This will give us the rate at which the braking system is converting mechanical energy to thermal energy.

I hope this helps guide you in solving the problem. Remember to always clearly define the problem and identify the known variables, and use the principles of physics to solve it.