Answer:
b. 0.034
Explanation:
The heat transfer coefficient of a material (U-value) is equal to the reciprocal of its R-value, therefore:
where
R is the R-value of the material
For the insulator in this problem,
R = 29
Substituting into the equation, we find the heat transfer coefficient:
To answer this problem, we will use the equations of motions.
Part (a):
For the ball to start falling back to the ground, it has to reach its highest position where its final velocity will be zero.
The equation that we will use here is:
v = u + at where
v is the final velocity = 0 m/sec
u is the initial velocity = 160 m/sec
a is acceleration due to gravity = -9.8 m/sec^2 (the negative sign is because the ball is moving upwards, thus, its moving against gravity)
t is the time that we want to find.
Substitute in the equation to get the time as follows:
v = u + at
0 = 160 - 9.8t
9.8t = 160
t = 160/9.8 = 16.3265 sec
Therefore, the ball would take 16.3265 seconds before it starts falling back to the ground
Part (b):
First, we will get the total distance traveled by the ball as follows:
s = 0.5 (u+v)*t
s = 0.5(160+0)*16.3265
s = 1306.12 meters
The equation that we will use to solve this part is:
v^2 = u^2 + 2as where
v is the final velocity we want to calculate
u is the initial velocity of falling = 0 m/sec (ball starting falling when it reached the highest position, So, the final velocity in part a became the initial velocity here)
a is acceleration due to gravity = 9.8 m/sec^2 (positive as ball is moving downwards)
s is the distance covered = 1306.12 meters
Substitute in the above equation to get the final velocity as follows:
v^2 = u^2 + 2as
v^2 = (0)^2 + 2(9.8)(1306.12)
v^2 = 25599.952 m^2/sec^2
v = 159.99985 m/sec
Therefore, the velocity of the ball would be 159.99985 m/sec when it hits the ground.
The heat energy lost is directly related to the shape of the object.
The answer for the following question is explained below.
- <u><em>Therefore the work done is 130 kilo Joules.</em></u>
Explanation:
Work:
A force causing the movement or displacement of an object.
Given:
mass of the person (m) = 65 kg
height of the cliff (h) = 2000 m
To calculate:
work done (W)
We know;
According to the formula:
<u>W = m × g × h</u>
Where;
m represents mass of the person
g represents the acceleration due to gravity
where the value of g is;
<u> g = 10 m/ s²</u>
h represents the height of the cliff
From the above formula;
W = 65 × 10 × 2000
W = 130,000 J
W = 130 Kilo Joules
<u><em>Therefore the work done is 130 kilo Joules.</em></u>
You get a repetative <span>increase in velocity </span>
