Answer: option 1. thermal expansion and contraction.
The thermostat uses the thermal expansion and contraction of metals: when the metal expands it acts as a switch, a coiled ribbon expands and the electric circuit is off, then the current stops. When the temperatures decrease, the coiled ribbon contracts and the circuit is on, then the current starts to flow and the resistance starts to radiate heat.
Answer:
7.745 feet
Explanation:
Data provided:
Length of the pole, L = 6 feet
Distance between the stake from the bottom of the pole, B = 4 feet
let the length of the rope be 'x'
Now,
The top of the pole, the bottom of the pole and the stake forms a right angled triangle.
Thus,
Using the concept of Pythagoras theorem,
we have
length of the pole as perpendicular, Distance between the stake from the bottom of the pole as base and length of the rope as hypotenuse
therefore,
L² + B² = x²
on substituting the values, we get
6² + 4² = x²
or
x = √60
or
x = 7.745 feet
Heat must be added to raise the temperature from 20.0 •C to 82 •C is
Q= (4200 x 1.8 + 880 x 1.3) x (82 - 20) = 539648J
Given:-
- Speed of the unicycle = 20 m/s
- Time taken = 15 s
To Find: Distance travelled by the unicycle.
We know,
s = vt
where,
- s = Distance travelled,
- v = Speed &
- t = Time taken.
Therefore,
s = (20 m/s)(15 s)
→ s = (20 m)(15)
→ s = 300 m (Ans.)
Answer:
x = A sin w t displacement in SHM
v = A w cos w t velocity in SHM
PE = 1/2 k x^2 = 1/2 k A^2 sin^2 w t
KE = 1/2 m v^2 = 1/2 m w^2 A^2 cos^2 w t
If KE = PE then
k sin^2 w t = m w^2 cos^2 w t
sin^2 wt / cos^2 w t = tan^2 w t = m w^2 / k
but k / m = w^2
So tan^2 w t = 1 and tan w t = 1 or w t = pi / 4 or theta = 45 deg
Then x = r sin w t = r sin 45 = .707 r