The rate of heat loss by radiation is equal to <u>-207.5kW</u>
Why?
To calculate the heat loss rate (or heat transfer rate) by radiation, from the given situation, we can use the following formula:
Where,
E, is the emissivity of the body.
A, is the area of the body.
T, are the temperatures.
S, is the Stefan-Boltzmann constant, which is equal to:
Now, before substitute the given information, we must remember that the given formula works with absolute temperatures (Kelvin), so, we need to convert the given values of temperature from Celsius degrees to Kelvin.
We know that:
So, converting we have:
Therefore, substituting the given information and calculating, we have:
Hence, we have that the rate of heat loss is equal to -207.5kW.
Answer: Both cannonballs will hit the ground at the same time.
Explanation:
Suppose that a given object is on the air. The only force acting on the object (if we ignore air friction and such) will be the gravitational force.
then the acceleration equation is only on the vertical axis, and can be written as:
a(t) = -(9.8 m/s^2)
Now, to get the vertical velocity equation, we need to integrate over time.
v(t) = -(9.8 m/s^2)*t + v0
Where v0 is the initial velocity of the object in the vertical axis.
if the object is dropped (or it only has initial velocity on the horizontal axis) then v0 = 0m/s
and:
v(t) = -(9.8 m/s^2)*t
Now, if two objects are initially at the same height (both cannonballs start 1 m above the ground)
And both objects have the same vertical velocity, we can conclude that both objects will hit the ground at the same time.
You can notice that the fact that one ball is fired horizontally and the other is only dropped does not affect this, because we only analyze the vertical problem, not the horizontal one. (This is something useful to remember, we can separate the vertical and horizontal movement in these type of problems)
Answer:
66.5N
Explanation:
F = kx
Where F = force
K = spring constant
x = compression
Given
K = 950N/m
x = 7.0cm
F = ?
First convert the compression to meters .
7.0cm = 7.0 x 0.01
= 0.07 meters
Therefore
F = 950 x 0.07
= 66.5N
Answer:
Number value and direction
Explanation:
Vectors are quantities that can be identified by value and direction . Examples are velocity and acceleration
