Answer:
-200 N
Explanation:
The cabinet moves at constant velocity, so that means there's no acceleration.
Applying Newton's second law to the cabinet:
∑F = ma
F + 200 = 0
F = -200
The friction force is 200 N in the opposite direction.
Answer:12.8 ft/s
Explanation:
Given
Speed of hoop ![v=26\ ft/s](https://tex.z-dn.net/?f=v%3D26%5C%20ft%2Fs)
height of top ![h=16\ ft](https://tex.z-dn.net/?f=h%3D16%5C%20ft)
Initial energy at bottom is
![E_b=\frac{1}{2}mv^2+\frac{1}{2}I\omega ^2](https://tex.z-dn.net/?f=E_b%3D%5Cfrac%7B1%7D%7B2%7Dmv%5E2%2B%5Cfrac%7B1%7D%7B2%7DI%5Comega%20%5E2)
Where m=mass of hoop
I=moment of inertia of hoop
=angular velocity
for pure rolling ![v=\omega R](https://tex.z-dn.net/?f=v%3D%5Comega%20R)
![I=mR^2](https://tex.z-dn.net/?f=I%3DmR%5E2)
![E_b=\frac{1}{2}mv^2+\frac{1}{2}mR^2\times (\frac{v}{R})^2](https://tex.z-dn.net/?f=E_b%3D%5Cfrac%7B1%7D%7B2%7Dmv%5E2%2B%5Cfrac%7B1%7D%7B2%7DmR%5E2%5Ctimes%20%28%5Cfrac%7Bv%7D%7BR%7D%29%5E2)
![E_b=mv^2=m(26)^2=676m](https://tex.z-dn.net/?f=E_b%3Dmv%5E2%3Dm%2826%29%5E2%3D676m)
Energy required to reach at top
![E_T=mgh=m\times 32.2\times 16](https://tex.z-dn.net/?f=E_T%3Dmgh%3Dm%5Ctimes%2032.2%5Ctimes%2016)
![E_T=512.2m](https://tex.z-dn.net/?f=E_T%3D512.2m)
Thus 512.2 m is converted energy is spent to raise the potential energy of hoop and remaining is in the form of kinetic and rotational energy
![\Delta E=676m-512.2m=163.8m](https://tex.z-dn.net/?f=%5CDelta%20E%3D676m-512.2m%3D163.8m)
Therefore
![163.8 m=mv^2](https://tex.z-dn.net/?f=163.8%20m%3Dmv%5E2)
![v=\sqrt{163.8}](https://tex.z-dn.net/?f=v%3D%5Csqrt%7B163.8%7D)
![v=12.798\approx 12.8\ ft/s](https://tex.z-dn.net/?f=v%3D12.798%5Capprox%2012.8%5C%20ft%2Fs)
Answer:
time is 3333.33 min or 55.55 hr
Explanation:
given data
reactor operating = 1 MW
negative reactivity = $5
power = 1 miliwatt
to find out
how long does it take
solution
we know here power coefficient that is
power coefficient = ![\frac{10^{6} }{10^{6} }](https://tex.z-dn.net/?f=%5Cfrac%7B10%5E%7B6%7D%20%7D%7B10%5E%7B6%7D%20%7D)
power coefficient = 1
so time required to reach power is
power = reactivity × time / power coefficient + reactor operating
1 ×
= -5 t / 1 + 1 × ![10^{6}](https://tex.z-dn.net/?f=10%5E%7B6%7D)
5t =
- ![10^{-3}](https://tex.z-dn.net/?f=10%5E%7B-3%7D)
t = 199999.99 sec
so time is 3333.33 min or 55.55 hr
After reading this whole question, I feel like I've already
earned 5 points !
-- Two satellites at the same distance, different masses:
The forces of gravity between two objects are directly
proportional to the product of the objects' masses. In
other words, the gravitational forces between the Earth
and an object on its surface are proportional to the mass of
the object. In other words, people with more mass weigh more
on the Earth, and the Earth weighs more on them.
If the satellites are both at the same distance from Earth,
then the Earth pulls on the one with more mass with greater
force, and also the one with more mass pulls on the Earth
with greater force.
-- Two satellites with the same mass, at different distances:
The forces of gravity between two objects are inversely
proportional to the square of the distance between them.
In other words, the gravitational
forces between the Earth
and an object are inversely proportional
to the square of
the distance between the object and the center of the Earth.
If
the satellites both have the same mass, then the Earth
pulls on the nearer one with greater force, and also the
nearer one pulls on the Earth with greater force.
-- Resistor in a circuit when the voltage changes:
The resistance depends on how the resistor was manufactured.
Its resistance is marked on it, and doesn't change. It remains
the same whether the voltage changes, the current changes,
the time of day changes, the cost of oil changes, etc.
If you increase the voltage in the circuit where that resistor is
installed, the current through the resistor increases. If the current
remains constant, then you can be sure that somebody snuck over
to your circuit when you weren't looking, and they either installed
another resistor in series with the original one to make the total
resistance bigger, or else they snipped the original one out of the
circuit and quickly connected one with more resistance in its place.
Answer:
meter, kilogram
Explanation:
Here we want to know how big the tiger is. This means that we want to measure its size and possibly its mass.
The size is actually a measure of the length of the tiger, and length is measured in meters.
The mass of an object, instead, is a measure of the "amount of matter" in the substance, and it is measured in kilograms.
The other options are wrong because:
- The second is the unit of time
- The candela is the unit of the luminous intensity
- The mole is the unit of the amount of substance, and it is used for gases
- The ampere is the unit of the current