Answer:
(a) the high of a hill that car can coast up (engine disengaged) if work done by friction is negligible and its initial speed is 110 km/h is 47.6 m
(b) thermal energy was generated by friction is 1.88 x 
J
(C) the average force of friction if the hill has a slope 2.5º above the horizontal is 373 N
Explanation:
given information:
m = 750 kg
initial velocity, 
= 110 km/h = 110 x 1000/3600 = 30.6 m/s
initial height, 
= 22 m
slope, θ = 2.5°
(a) How high a hill can a car coast up (engine disengaged) if work done by friction is negligible and its initial speed is 110 km/h?
according to conservation-energy
EP = EK
mgh = 
gh = 
h = 
= 47.6 m
(b) If, in actuality, a 750-kg car with an initial speed of 110 km/h is observed to coast up a hill to a height 22.0 m above its starting point, how much thermal energy was generated by friction?
thermal energy = mgΔh
= mg (h - )
= 750 x 9.8 x (47.6 - 22)
= 188160 Joule
= 1.88 x J
(c) What is the average force of friction if the hill has a slope 2.5º above the horizontal?
f d = mgΔh
f = mgΔh / d,
where h = d sin θ, d = h/sinθ
therefore
f = (mgΔh) / (h/sinθ)
= 1.88 x /(22/sin 2.5°)
= 373 N
Weight equals mass*gravity
W = mg
Given m = 3.1 kg, g = 9.8 m/s^2
W = (3.1)(9.8)
W = 30.38
Answer:
The impression of the image on the retina lasts for about 1/16th of a second after the removal of the object. If a burning stick of incense is revolved at a rate of more than sixteen revolutions per second, we see a circle of red light due to persistence of vision.
Explanation:
PART A)
Conductivity of insulator is very small as there is no free electrons to conduct the current trough that medium
So here number of conduction electrons are very less in insulators
PART B)
Resistance is the property of a conducting medium which will oppose the flow of current trough it
Resistance of wire directly depends on its length so resistance of long wire will be more than the resistance of short wire
Resistance inversely depends on the area so if a wire has more crossectional area then its resistance must be small
PART C)
power of light bulb is defined as rate of electrical energy
it is given by formula
P = i V
here we know that
i = 1.46 A
V = 120 volts
so power is given as
1. friction between water molecules
2. the wave spreads out onto a larger and larger area, so per unit area, the energy of the wave goes down
