Download App

Work, Energy, and Power — Physics STD 11 Science — Question

Rajasthan BoardEnglish MediumSTD 11 SciencePhysicsWork, Energy, and Power3 Marks
Question
Why is electrical power required at all when the elevator is descending? Why should there be a limit on the number of passengers in this case?
✓

Answer

When elevator is descending then it is not its free fall under gravity it descends with uniform speed. Power is required to decrease the velocity due to free fall.
Power of motor or system of an elevator is constant and a limited or specified power can stop the speed of freely falling of passenger along with elevator.

Need a full question paper?

Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.

Start Generating Free

Explore more

More "3 Marks Question" from Work, Energy, and Power→Work, Energy, and Power — all question types→Physics STD 11 Science question papers→Rajasthan Board STD 11 Science question papers→Rajasthan Board question paper generator→

Similar questions

A man uses a concave mirror for shaving. He keeps his face at a distance of 25cm from the mirror and gets an image which is 1.4 times enlarged. Find the focal length of the mirror.
→
Explain with the suitable example that a reversible process must be carried slowly and a fast process is necessarily irreversible.
→
Calculate the energy that can be obtained from 1kg of water through the fusion reaction
2H + 2H → 3H + p.
Assume that 1.5 × 10-2% of natural water is heavy water D2O (by number of molecules) and all the deuterium is used for fusion.
→
A spring compressed by 0.1m develops a restoring force of 10N. A body of mass 4kg is placed on it. Deduce the (i) force constant of the spring (ii) depression of the spring under the weight of the body and (iii) period of oscillation, if the body is disturbed.
→
A uniform chain of mass m and length l overhangs a table with its two third part on the table. Find the work to be done by a person to put the hanging part back on the table.
→
Explain why:
An optical pyrometer (for measuring high temperatures) calibrated for an ideal black body radiation gives too low a value for the temperature of a red hot iron piece in the open, but gives a correct value for the temperature when the same piece is in the furnace.
→
A motorboat covers the distance between two ports on the river in t1 = 8hr and t2 = 12hr downstream and upstream respectively. What is the time required for the boat to cover this distance in still water?
→
A body of mass 5kg executes S.H.M. of amplitude of 0.5m. If the force constant is 100Nm-1, calculate
  1. Its time period.
  2. Its maximum kinetic energy, maximum potential energy and total energy.
→
Consider a Carnot’s cycle operating between T1 = 500K and T2=300K producing 1k J of mechanical work per cycle. Find the heat transferred to the engine by the reservoirs.
→
A SONAR system fixed in a submarine operates at a frequency 40.0 kHz. An enemy submarine moves towards the SONAR with a speed of 360km h–1. What is the frequency of sound reflected by the submarine? Take the speed of sound in water to be 1450m s–1.
→