Answer:
Explanation:
In the decibel scale , intensity of sound changes logarithmically as follows
Value in decibel scale , the value of I₀ = 10⁻¹² W /m².
Putting the values
W/m²
Similarly for 54 dB sound intensity can be given as follows
I = 10⁻¹² x
W / m²
For intensity of sound the relation is as follows
I = 2π²υ²A²ρc where υ is frequency , A is amplitude , ρ is density of air and c is velocity of sound .
Putting the given values for 71 dB
= 2π² x 504²xA²x 1.21 x 346
A² = 60.03 x 10⁻¹⁶
A = 7.74 x 10⁻⁸ m
For 54 dB sound
= 2π² x 504²xA²x 1.21 x 346
A² = 1.1978 x 10⁻¹⁶
A = 1.1 x 10⁻⁸ m
A) diagram is shown on the image below
b) Mass m = 450/9.8 = 45.918 KgNet upward force = T + T = 2T = 620 NNet downward force = 290 + 160 = 450 NResultant force F = Net upward force - Net downward force ma = 620 - 450 45.918 a = 170 Acceleration a = 170/45.918 =
3.7 m/s^2 (upward)Here Net upward force > Net downward force, So the resultant force directed upwards, hence acceleration will be
upward.
(c)Consider the case of boy alone, then from Newtons law of motion we can write Net force F = n + T - 290 ma = n + 310 - 290 where m = 290/9.8 = 29.59 Kg 29.59 * 3.7 = n + 20 109.483 = n + 20 n =
89.483 N
Answer:
y maximum 3.54 m, value X 2.35 m
Explanation:
We have a projectile launch problem, let's calculate the maximum height of the projectile, where the vertical speed must be zero
Vyf² = Vyo² - 2g (Y-Yo)
Where Yo is the initial height of the ramp 1.5 m
0 = Vyo² -2g (Y-Yo)
Y-Yo = Voy² / 2g
Y = Yo + Voy² / 2g
Let's calculate the velocity components using trigonometry
Voy = vo without T
Vox = Vo cost
Voy = 7.3 sin 60
Vox = 7.3 cos 60
Voy = 6.32 m / s
Vox = 3.65 m / s
Let's calculate the maximum height
Y = 1.5 +6.32²/2 9.8
Y = 3.54 m
This is the maximum height from the ground
b) They ask us for the position of this point horizontally, we can calculate it looking for the time it took for the skateboarder to reach the highest point
Vfy = Voy - gt
0 = Voy - gt
t = Voy / g
t = 6.32 / 9.8
t = 0.645 s
Since there is no acceleration on the x-axis, we have a uniform movement, we can calculate the distance for this time
X = Vox t
X = 3.65 0.645
X= 2.35 m
Given that,
Horizontal force, F = 600 N
A mover pushes a dresser 9 meters across a bedroom.
To find,
The work done by the mover.
Solution,
The work done by an object is given by :
W = Fd
Where d is distance
W = 600 N × 9 m
= 5400 J
So, the work done by the mover is 5400 J.
Answer:
t should be 3.57 second
Explanation:
Formula used is v = u+at
In which v is final velocity, u is initial velocity, a is acceleration and t is time.
Substitute each of the info given into the formula and calculate.
49 = 24 + (7)t
t = 3.57s