20W = 20 J/s
Energy expended during climbing stairs = 50 W of energy/stair = 50J/stair
For 20 stairs, Total energy = 50x20 = 1000 J
This can light bulbs for, T= 1000J/20 J/s =50 seconds
Answer:

Explanation:
The strength of an electric field E produced by a single charge Q at a distance d from it is given by the formula:
, where K represents the Coulomb constant.
Since the electric field E is derived from the Coulomb Force per unit charge using a positive test charge, the field's units will be in units of Newtons/Coulomb, and be the formula for the Coulomb electric force between to charges (Q1 and Q2),

but modified with only one charge showing in the numerator of the expression.
The equation for Hall voltage Vh is:
Vh=v*B*w, where v is the velocity of the strip, B is the magnitude of the magnetic field, and w is the width of the strip.
v=25 cm/s = 0.25 m/s
B=5.6 T
w= 1.2 mm = 0.0012 m
We input the numbers into the equation and get:
Vh= 0.25*5.6*0.0012 = 0.00168 V
The maximum Hall voltage is Vh= 0.00168 V.
Answer:
Explanation:
Given that,
A light bulb has a resistance of 2.9ohms
R = 2.9 ohms
And a battery of 1.5V is applied
V = 1.5 V
We want to find the rate of energy transformed
First we need to know what rate of energy is
Rate of energy implies that we want to find power. Power is the rate at which work is done
P = Workdone / time
Then,
In electronic, the power dissipated by a resistor is given as
P = V² / R
P = 1.5² / 2.9
P = 0.7759 W
P ≈ 0.776 W
So, the rate at which electrical energy transformed in the lightbulb is 0.776 Watts
Answer:
magnitude = 7.446 km, direction = 75.22° north of east
Explanation:
From the questions,
To get the the magnitude of the resultant vector we use Pythagoras theorem
a² = b²+c²
From the diagram,
y² = 1.9²+7.2²
y² = 55.45
y = √(55.45)
y = 7.446 km.
The direction of the dolphin is given as,
θ = tan⁻¹(7.2/1.9)
θ = tan⁻¹(3.7895)
θ = 75.22° north of east
Hence the magnitude of the resultant vector = 7.446 km, and it direction is 75.22° north of east