Answer:
the skateboard pushes up
Explanation:
newton's 3rd law says for every action, there's an equal and opposite reaction, so when his feet push on the skateboard, the skateboard pushes back up.
Answer:
Weight = 3.924 N
Bouyant force = 2.5N
Apperent weight= 1.424N
Explanation:
Radius of the sphere = 0.0165 m
Volume of sphere = (4πr³)/3
Volume = 4.189*(4.49*10^-6)
Volume = 1.88*10^-5
For the weight.
Mass = density* volume
Mass = 2.14*10^4 *(1.88*10^5)
Mass = 0.4 kg.
Weight = mass * acceleration due to gravity
Weight = 0.4*9.81
Weight = 3.924 N
For the buoyant force Fb
Fb = volume * density of fluid* acceleration
Fb = (1.88*10^5)*1.36 × 10^ 4*9.81
Fb = 2.5N
For Apperent weight
True weight - buoyant force = Apperent weight.
3.924- 2.5N= 1.424N
Answer:
<em>The sale price is $498,30</em>
Explanation:
<u>Percentages</u>
The selling (list) price on a dishwasher is $906.
The store advertises a 45% markdown on that price.
The markdown is calculated as follows:
45% of $906 = 45 * 906 / 100 = $407.70
The sale price (retail) is calculated as the selling price minus the markdown.
Thus, the sale price is:
$906 - $407.70 = $498,30
The sale price is $498,30
The first one is B. I think and the second one is A.
Answer:
See description
Explanation:
Frist we need to know the longitude of tape which is unwinding. Such relationship can be obtained with arc length. An arc length is the distance bewteen two points in a curve.
The relationship is:
![S = \theta r](https://tex.z-dn.net/?f=S%20%3D%20%5Ctheta%20r)
Where
is the arc length or distance, theta is the angle that results from the initial point of the measure to the final point, and r is the radius of a circumference.
Now let
be length the unwinded tape. Change
by
and you ge the relationship:
![x(t) = \theta r](https://tex.z-dn.net/?f=x%28t%29%20%3D%20%5Ctheta%20r)
if you unwind the tape by one revolution (
) you get the perimeter of a cricle
, if you unwind it two times then
and so on.
Then we have that the derivative of
is ![v(t)](https://tex.z-dn.net/?f=v%28t%29)
so we replace:
![\frac{dx}{dt} = v(t)\\ \frac{dx}{dt}=v(t)=\frac{d\theta}{dt}](https://tex.z-dn.net/?f=%5Cfrac%7Bdx%7D%7Bdt%7D%20%3D%20v%28t%29%5C%5C%20%5Cfrac%7Bdx%7D%7Bdt%7D%3Dv%28t%29%3D%5Cfrac%7Bd%5Ctheta%7D%7Bdt%7D)
the derivative of theta with respect to t is ω(t) by definition:
![\frac{d\theta}{dt}=\omega(t)\\ =>\frac{dx}{dt}=v(t)=\omega(t) r\\=>\frac{v(t)}{r}=\omega(t)](https://tex.z-dn.net/?f=%5Cfrac%7Bd%5Ctheta%7D%7Bdt%7D%3D%5Comega%28t%29%5C%5C%20%3D%3E%5Cfrac%7Bdx%7D%7Bdt%7D%3Dv%28t%29%3D%5Comega%28t%29%20r%5C%5C%3D%3E%5Cfrac%7Bv%28t%29%7D%7Br%7D%3D%5Comega%28t%29)
The result is the relationship between angular velocity and the velocity and tangential velocity at the point r