Answer:a
Explanation:
We have to lift the load two loads up one story, so energy required is
let m be the mass of each load and h is the height of each story
Energy 

Here energy gained is the potential energy which depends upon the datum(floor).
For lifting one load up one story
Energy required

thus
is half of 
So option a is correct
Answer:
a) 2.4 mm
b) 1.2 mm
c) 1.2 mm
Explanation:
To find the widths of the maxima you use the diffraction condition for destructive interference, given by the following formula:

a: width of the slit
λ: wavelength
m: order of the minimum
for little angles you have:

y: height of the mth minimum
a) the width of the central maximum is 2*y for m=1:

b) the width of first maximum is y2-y1:
![w=y_2-y_1=\frac{(500*10^{-9}m)(1.2m)}{0.50*10^{-3}m}[2-1]=1.2mm](https://tex.z-dn.net/?f=w%3Dy_2-y_1%3D%5Cfrac%7B%28500%2A10%5E%7B-9%7Dm%29%281.2m%29%7D%7B0.50%2A10%5E%7B-3%7Dm%7D%5B2-1%5D%3D1.2mm)
c) and for the second maximum:
![w=y_3-y_2=\frac{(500*10^{-9}m)(1.2m)}{0.50*10^{-3}m}[3-2]=1.2mm](https://tex.z-dn.net/?f=w%3Dy_3-y_2%3D%5Cfrac%7B%28500%2A10%5E%7B-9%7Dm%29%281.2m%29%7D%7B0.50%2A10%5E%7B-3%7Dm%7D%5B3-2%5D%3D1.2mm)
Answer:
The value is
Explanation:
From the question we are that
The velocity 
The time taken is
The total mass of the train is 
Generally the average power delivered is mathematically represented as
=>
=>
In order to make things easier to describe and explain, let's call
the resistance of each bulb 'R', and the battery voltage 'V'.
a). In series, the total resistance is 3R.
In parallel, the total resistance is R/3.
Changing from series to parallel, the total resistance of the circuit
decreases to 1/9 of its original value.
b). In series, the total current is V / (3R) .
In parallel, the total current is 3V / R .
Changing from series to parallel, the total current in the circuit
increases to 9 times its original value.
c). In series, the power dissipated by the circuit is
(V) · V/3R = V² / 3R .
In parallel, the power dissipated by the circuit is
(V) · 3V/R = 3V² / R .
Changing from series to parallel, the power dissipated by
the circuit (also the power delivered by the battery) increases
to 9 times its original value.