Answer:
t = 23.92 s
Explanation:
Newton's second law:
∑F = m*a Formula (1)
∑F : algebraic sum of the forces in Newton (N)
m : mass s (kg)
a : acceleration (m/s²)
We define the x-axis in the direction parallel to the movement of the block and the y-axis in the direction perpendicular to it.
Forces acting on the block
W: Weight of the block : In vertical direction, downward
FN : Normal force : perpendicular to the floor, upward
fk : Kinetic friction force: parallel to the floor and opposite to the movement
F = 86.4 N , in the direction of the motion
Calculated of the W
W= m*g
W= 16.8 kg* 9.8 m/s² = 164.64 N
Calculated of the FN
We apply the formula (1)
∑Fy = m*ay ay = 0
FN - W = 0
FN = W
FN = 164.64 N
Calculated of the fk
fk = μk*FN
fk = 0.426* 164.64 N
fk = 70.13 N
We apply the formula (1) to calculated acceleration of the block:
∑Fx = m*ax , ax= a : acceleration of the block
F - fk = m*a
86.4 -70.13 = (16.8)*(-a)
16.26 = (16.8)*(-a)
a = -(16.26 )/ (16.8)
a = - 0.97 m/s²
Kinematics of the block
Because the block moves with uniformly accelerated movement we apply the following formula :
vf = v₀ + a*t Formula (2)
Where:
t: time interval (m)
v₀: initial speed (m/s)
vf: final speed (m/s)
Data:
v₀ = 23.2 m/s
vf = 0
a = -0.97 m/s²
Time it takes for the block to stop
We replace data in the formula (2) to calculate the time
vf= v₀+a*t
0 = 23.2+( -0.97)*t
(0.97)*t = 23.2
(0.97)*t = 23.2
t = 23.2 / (0.97)
t = 23.92 s
4959167 is how many cubic meters in 10,000 gallons of water
I have the same physics class , so the answer would be 0.6
E S *
The "E" represents Earth, "S" represent Sun, and the "*" represents the nearest star(which is Proxima Centauri).
The main thing to worry about here is units, so ill label everything out.
D'e,s'(Distance between earth and sun) = .<span>00001581 light years
D'e,*'(Distance between earth and Proxima) = </span><span>4.243 light years
Now this is where it gets fun, we need to put all the light years into centimeters.(theres alot)
In one light year, there are </span>9.461 * 10^17 centimeters.(the * in this case means multiplication) or 946,100,000,000,000,000 centimeters.
To convert we multiply the light years we found by the big number.
D'e,s'(Distance between earth and sun) = 1.496 * 10^13 centimeters<span>
D'e,*'(Distance between earth and Proxima) = </span><span>4.014 * 10^18 centimeters
</span>
Now we scale things down, we treat 1.496 * 10^13 centimeters as a SINGLE centimeter, because that's the distance between the earth and the sun. So all we have to do is divide (4.014 * 10^18 ) by (<span>1.496 * 10^13 ).
Why? because that how proportions work.
As a result, you get a mere 268335.7 centimeters.
To put that into perspective, that's only about 1.7 miles
A lot of my numbers came from google, so they are estimations and are not perfect, but its hard to be on really large scales.</span>
Apart from cutaneous respiration<span> present in all </span>species<span>, most lissamphibians are born in an aquatic larval stage with gills. After metamorphosis, they develop lungs to breathe on land. The larvae of urodeles and apods present external, filamentous and highly branched gills which allow them to breathe underwater.
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