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.
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.
Explore more
Similar questions
A truck tows a trailer of mass 1200kg at a speed of 10ms-1 on a level road. The tension in the coupling is 1000N. What is the power extended on the trailer?
Find the tension in the coupling when the truck ascends a road having an inclination of 1 in 6. Assume that the frictional resistance on the inclined plane is the same as that on the level road.
Find the tension in the coupling when the truck ascends a road having an inclination of 1 in 6. Assume that the frictional resistance on the inclined plane is the same as that on the level road.
In the relation $\text{p}=\Big(\frac{\text{a}}{\text{b}}\Big)^{\text{e}^{-\Big(\frac{\text{az}}{\theta}\Big)}},\text{p}$ is the pressure, Z is the distance, and is the temperature. What is the dimensional formula of p?
→A body starts accelerating uniformly with a from a velocity ‘u' and travels in a straight line. Prove that it covers a length of $\text{u}+\frac{\text{a}}{2}(2\text{t}-1)$ in the tth second of motion.
→A metre scale made of steel is calibrated at 20°C to give correct reading. Find the distance between the 50cm mark and the 51cm mark if the scale is used at 10°C. Coefficient of linear expansion of steel is 1.1 × 10-5 °C-1.
An open pipe is suddenly closed at one end with the result that the frequency of sound harmonic of the closed pipe is found to be higher by 100Hz than the fundamental frequency of the open pipe. Calculate the fundamental frequency of the open pipe.
An aircraft executes a horizontal loop of radius 1.00 km with a steady speed of 900 km/h. Compare its centripetal acceleration with the accelertion due to gravity.
What is the temperature of the steel-copper junction in the steady state of the system shown in Fig. 10.15. Length of the steel rod $=15.0 cm$, length of the copper rod $=10.0 cm$, temperature of the furnace $=300^{\circ} C$, temperature of the other end $=0{ }^{\circ} C$. The area of cross section of the steel rod is twice that of the copper rod. (Thermal conductivity of steel $=50.2 J s ^{-1} m ^{-1} K ^{-1}$; and of copper $\left.=385 J s ^{-1} m ^{-1} K ^{-1}\right)$.
→Explain how momentum conservation explains explosion of a mass at rest.
Two particles of masses m1 and m2 are joined by a light rigid rod of length r. The system rotates at an angular speed co about an axis through the centre of mass of the system and perpendicular to the rod. Show that the angular momentum of the system is $\text{L}=\mu\text{r}^2\omega$ where $\mu$ is the reduced mass of the system defined as $\mu=\frac{\text{m}_1\text{m}_2}{\text{m}_1+\text{m}_2}.$
→Whenever a photon is emitted by hydrogen in Balmer series, it is followed by another photon in Lyman series. What wavelength does this latter photon correspond to?