-- <em>A soccer ball eventually stops because its energy disappears.</em> No. Energy does NOT "disappear". That would exactly violate the whole concept of energy conservation.
-- <em>When a light bulb is turned on, electrical energy is converted to light and heat.</em> <em>Gosh Yes !</em> This statement tells where the energy comes from, what happens to it, and where it goes. In a sloppy floppy way, it incorporates all of the highlights of energy conservation.
-- <em>An automobile engine burns gasoline to converts its chemical energy to electrical energy</em>. No. When you look closely at this statement, MOST of the energy involved is missing and unaccounted for. The statement only accounts for starting the motor and running the car radio. It completely ignores the huge amount of mechanical energy produced from the gasoline.
Answer:
15.68 m/s
Explanation:
Given that,
She catches the ball 3.2 s later at the same height from which it was thrown.
When it reaches the maximum height, its height is equal to 0.
It will move under the action of gravity.
2 here comes for the time of ascent and descent.
So,
So, the initial upward speed of the ball is 15.68 m/s.
Answer:
The wavelength of radio waves is 2.85 m.
(B) is correct option.
Explanation:
Given that,
Frequency = 105 MHz
We need to calculate the wavelength of radio waves
Using formula of wave velocity
Where, v = wave speed
f = frequency
= wavelength
Put the value into the formula
Hence, The wavelength of radio waves is 2.85 m.
Answer:
The angular velocity of the wheel in terms of d, F, and I is, ω = d/t (F/I α) s⁻¹
Explanation:
Given,
The angular velocity ω
The displacement d
The magnitude of the applied force, F
The moment of inertia of the wheel I = mr²
The angular velocity can be written as
ω = v /r
where,
v - linear velocity
r - radius of the wheel
ω = d/t (1/r) (∵ v = d /t)
The force can be written as,
F = m a
= m α r (∵ a = α r)
Multiplying both sides by r
F r = m r² α
F r = I α (∵ I = mr²)
r = I α / F
Substituting in the above equation for ω
ω = d/t (F/I α) s⁻¹
Hence, the angular velocity of the wheel in terms of d, F, and I is, ω = d/t (F/I α) s⁻¹