Ali and Abdi go for a walk along an abandoned railroad truck , Ali puts one ear next to a rail, while Abdi 300m away taps in the
1 answer:
Answer:
Ali hear the sound in 0.046 seconds.
Explanation:
Given:
Distance between Ali and Abdi = 300m
Speed of sound in steel = 6500m/s
To Find :
How much sooner does Ali hear the sound = ?
Solution:
We can find the time in which the sound made by Abdi with a stone on the rail by using the speed formula
We know that
On substituting the given values,
Time = 0.046 seconds
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To explain, I will use the equations for kinetic and potential energy:
Potential energy is the potential an object has to move due to gravity. An object can only have potential energy if 1) <u>gravity is present</u> and 2) <u>it is above the ground at height h</u>. If gravity = 0 or height = 0, there is no potential energy. Example:
An object of 5 kg is sitting on a table 5 meters above the ground on earth (g = 9.8 m/s^2). What is the object's gravitational potential energy? <u>(answer: 5*5*9.8 = 245 J</u>)
(gravitational potential energy is potential energy)
<h3>Kinetic energy</h3>Kinetic energy is the energy of an object has while in motion. An object can only have kinetic energy if the object has a non-zero velocity (it is moving and not stationary). An example:
An object of 5 kg is moving at 5 m/s. What is the object's kinetic energy? (<u>answer: 5*5 = 25 J</u>)
<h3>Kinetic and Potential Energy</h3>Sometimes, an object can have both kinetic and potential energy. If an object is moving (kinetic energy) and is above the ground (potential), it will have both. To find the total (mechanical) energy, you can add the kinetic and potential energies together. An example:
An object of 5 kg is moving on a 5 meter table at 10 m/s. What is the objects mechanical (total) energy? (<u>answer: KE = .5(5)(10^2) = 250 J; PE = (5)(9.8)(5) = 245 J; total: 245 + 250 = 495 J</u>)
Complete question:
A light bulb emits light that travels uniformly in all directions. Detailed measurements show that at a distance of 56 m from the bulb, the amplitude of the electric field is 3.78 V/m. What is the average intensity of the light?
Answer:
The average intensity of the light is 0.02 W/m²
Explanation:
Given;
Amplitude of the electric field, E₀ = 3.78 V/m
The average intensity of the light is calculated as follows;
where;
is the average intensity of the light
c is speed of light = 3 x 10⁸ m/s
Therefore, the average intensity of the light is 0.02 W/m²