1answer.
Ask question
Login Signup
Ask question
All categories
  • English
  • Mathematics
  • Social Studies
  • Business
  • History
  • Health
  • Geography
  • Biology
  • Physics
  • Chemistry
  • Computers and Technology
  • Arts
  • World Languages
  • Spanish
  • French
  • German
  • Advanced Placement (AP)
  • SAT
  • Medicine
  • Law
  • Engineering
Cerrena [4.2K]
3 years ago
9

A hand lifts a block vertically upward at constant velocity. The work done by gravity on the block ____ if the system consists o

f the block only. The work done by gravity on the block ____ if the system consists of the block and the earth. AND WHY?
1. is zero, is zero2. is zero, is negative3. is zero, is positive4. is negative, is negative5. is positive, is positive
Physics
1 answer:
adelina 88 [10]3 years ago
6 0

Answer:

If the system consists of the block only, the work done by the gravity is negative.

If the system consists of the block and the earth the work done by the gravity is zero.

Explanation:

If the system consists of the block only, then the system experiences two external forces: one exerted by the hand that lifts the block vertically upward and other exerted by the earth (gravity), which is opposed to the movement of the system, so the work done by gravity is negative.

On the other hand, if the system consists of the block and the earth, then only exists a external force which is the exerted by the hand. So, the force exerted by gravity is zero.

You might be interested in
Why do you rotate when you hold a spinning wheel?
choli [55]
When you hold a spinning wheel, the wheel and you, chair included, form a system that obeys the principle of "conservation of angular momentum". This means that any changes in angular momentum within the system must accompanied by an equal and opposite change, so the net force is zero.
4 0
3 years ago
A charged particle moves in a circular path in a uniform magnetic field.Which of the following would increase the period of the
Bond [772]

Answer:

Increasing its charge

Increasing the field strength

Explanation:

For a charged particle moving in a circular path in a uniform magnetic field, the centripetal force is provided by the magnetic force, so we can write:

qvB = m\frac{v^2}{r}

where

q is the charge

v is the velocity

B is the magnetic field

m is the mass

r is the radius of the orbit

The period of the motion is

T=\frac{2\pi r}{v}

Re-arranging for r

r=\frac{Tv}{2\pi}

And substituting into the previous equation

qvB = m \frac{Tv^3}{2\pi}

Solving for T,

T=\frac{2\pi q B}{m v^2}

So we see that the period is:

- proportional to the charge and the magnetic field

- inversely proportional to the mass and the square of the speed

So the following will increase the period of the particle's motion:

Increasing its charge

Increasing the field strength

4 0
3 years ago
a mass of 1.00 kg of water at temperature T is poured from a height of 0.100 km into a vessel containing water of the same tempe
Mariana [72]

Answer:

1.34352 kg

Explanation:

m_w = Mass of water falling = 1 kg

h = Height of fall = 0.1 km

\Delta T = Change in temperature = 0.1

c = Specific heat of water = 4186 J/kg K

g = Acceleration due to gravity = 9.81 m/s²

m_v = Mass of water in the vessel

Here the potential energy will balance the internal energy

m_wgh=m_wc\Delta T+m_vc\Delta T\\\Rightarrow m_v=\dfrac{m_wgh-m_wc\Delta T}{c\Delta T}\\\Rightarrow m_v=\dfrac{m_wgh}{c\Delta T}-m_w\\\Rightarrow m_v=\dfrac{1\times 9.81\times 100}{4186\times 0.1}-1\\\Rightarrow m_v=1.34352\ kg

Mass of the water in the vessel is 1.34352 kg

6 0
3 years ago
) each plate of a parallel-plate air-filled capacitor has an area of 0.0020 , and the separation of the plates is an electric fi
Dvinal [7]
I attached the full question.
We know that for a parallel-plate capacitor the surface charge density is given by the following formula:
\sigma=\varepsilon_0 \frac{V}{d}
Where V is the voltage between the plates and d is separation.
Voltage is by definition:
V=Ed
Voltage is analog to the mechanical work done by the force.
Above formula is correct only If the field is constant, and we can assume that it is since no function has been given.
The charge density would then be:
\sigma=\varepsilon_0 \frac{Ed}{d}=\varepsilon_0E\\
\sigma= 8.85\cdot10^{-12}\cdot 2.1\cdot 10^6= 0.0000185\frac{c}{m^2}
Please note that elecric permittivity of air is very close to  elecric permittivity of vacum, it is common to use them <span>interchangeably</span>.

6 0
3 years ago
What is a wavelength of sound wave moving at 340m/s with frequency of 256hz
zimovet [89]
V = 340 m/s
f = 256 Hz
lambda (wavelength)

v = f*lambda
340 = 256 * lambda
340/256 = lambda
lambda = 1.328 m 
5 0
3 years ago
Other questions:
  • Which statement is accurate about mass and weight?
    5·1 answer
  • Technician A says that power is the rate that energy is stored. Technician B says that power refers to the rate that energy is t
    8·1 answer
  • At time t = 0 an elevator starts moving upward from the ground at a constant speed vo. At a later time t = T1 = 2.35s a marble i
    13·1 answer
  • The particles of a more dense substance are closer together
    14·2 answers
  • Please help its for science
    12·2 answers
  • which way would 2 negatively charged balloons naturally move? what would that do to the amount of potential energy stored in the
    11·1 answer
  • If a wheel rotates 5 times in 90 seconds, what is the period and frequency
    7·1 answer
  • Does the shape of molecule matter? why?​
    6·2 answers
  • Draco pushes a 3.2kg box with 1.5N of force. What is the resultant acceleration?
    13·1 answer
  • Ram and Ajay are trying to move a heavy box. Ram is applying 100N and Ajay is
    10·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!