In most calendar years there are two lunar eclipses; in some years one or three or none occur. Solar eclipses occur two to five times a year, five being exceptional
Answer:

Explanation:
As we know that the wheel is rotated at constant angular speed
so here we can say that the angular speed is given as



now the moment of inertia of all passengers is given as


now work done by machine must be equal to kinetic energy of the system
so we will have



A variable is any factor, trait, or condition that can exist in differing amounts or types. An experiment usually has three kinds of variables: independent, dependent, and controlled. The independent variable is the one that is changed by the scientist.
Answer:
185.95 μsec
Explanation:
Given that:
Sine wave = 

Sinusodial signal
= 50 kHz = 
Rise time is said to be defined as the time needed for a pulse to rise from 10% - 90% of maximum rate.
∴
= 10% = 0.1 Am
=90% = 0.9 Am
Using sine wave for
; we have:
= 0.1 Am
= 0.1

= 5.7392


Using sine wave for
; we have:
= 0.9 Am

= 
= 64.158
= 
= 
Change in rise time
=
- 
= 
= 
= 
since;
= 50 kHz = 
= 
= 1.85952 × 10⁻⁴
= 185.952 × 10⁻⁶ sec
= 185.95 μ sec
∴ The rise in time in (μ sec) for the sinosodial signal at 50 kHz = 185.95 μ sec