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kiruha [24]
4 years ago
12

A student gives a 5.0 kg box a brief push causing the box to move with an initial speed of 8.0 m/s along a rough surface. The bo

x experiences a friction force of 30 N as it slows to a stop. How long does it take the box to stop?
Physics
1 answer:
WITCHER [35]4 years ago
5 0

Answer:

The time taken to stop the box equals 1.33 seconds.

Explanation:

Since frictional force always acts opposite to the motion of the box we can find the acceleration that the force produces using newton's second law of motion as shown below:

F=mass\times acceleration\\\\\therefore acceleration=\frac{Force}{mass}

Given mass of box = 5.0 kg

Frictional force = 30 N

thus

acceleration=\frac{30}{5}=6m/s^{2}

Now to find the time that the box requires to stop can be calculated by first equation of kinematics

The box will stop when it's final velocity becomes zero

v=u+at\\\\0=8-6\times t\\\\\therefore t=\frac{8}{6}=4/3seconds

Here acceleration is taken as negative since it opposes the motion of the box since frictional force always opposes motion.

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Which of the following statements is/are true? Check all that apply. Check all that apply. The total mechanical energy of a syst
Taya2010 [7]

Answer:

1) True, 2) True, 3) False, 4) False, 5) False

Explanation:

1) True. Dissipative energy cannot be recovered, in general it is a form of heat

2) True. The dissipation can be by radiation, heat

3) False. Mechanical energy is divided into K and U but not in equal parts

4) False. When there are dissipative interactions, part of the mechanical energy is set in the form of heat, so its value decreases

5) False. Mechanical energy is the sum of those two energies

8 0
3 years ago
A wire carrying an electric current is often likened to a pipe carrying water. What part of this analogy is incorrect?
tamaranim1 [39]

In a direct current (DC) electrical circuit, the voltage (V in volts) is an expression of the available energy per unit charge which drives the electric current (I in amperes) around a closed circuit. Increasing the resistance (R in ohms) will proportionately decrease the current which may be driven through the circuit by the voltage.

Each quantity and each operational relationship in a battery-operated DC circuit has a direct analog in the water circuit. The nature of the analogies can help develop an understanding of the quantities in basic electric ciruits. In the water circuit, the pressure P drives the water around the closed loop of pipe at a certain volume flow rate F. If the resistance to flow R is increased, then the volume flow rate decreases proportionately. You may click any component or any relationship to explore the the details of the analogy with a DC electric circuit.

6 0
4 years ago
Consider a hydrogen atom in the n = 1 state. The atom is placed in a uniform B field of magnitude 2.5 T. Calculate the energy di
dlinn [17]

Answer:

E=29\times 10^{-5}eV

Explanation:

For n-=1 state hydrogen energy level is split into three componets in the presence of external magnetic field. The energies are,

E^{+}=E+\mu B,

E^{-}=E-\mu B,

E^{0}=E

Here, E is the energy in the absence of electric field.

And

E^{+} and E^{-} are the highest and the lowest energies.

The difference of these energies

\Delta E=2\mu B

\mu=9.3\times 10^{-24}J/T is known as Bohr's magneton.

B=2.5 T,

Therefore,

\Delta E=2(9.3\times 10^{-24}J/T)\times 2.5 T\\\Delta E=46.5\times 10^{-24}J

Now,

Delta E=46.5\times 10^{-24}J(\frac{1eV}{1.6\times 10^{-9}J } )\\Delta E=29.05\times 10^{-5}eV\\Delta E\simeq29\times 10^{-5}eV

Therefore, the energy difference between highest and lowest energy levels in presence of magnetic field is E=29\times 10^{-5}eV

6 0
4 years ago
Putting a beaker of water in a microwave and turning it on for a minute or two will increase the temperature of the water. Descr
Jobisdone [24]

Answer:

The equipment to use is: a beaker, a fixed amount of water, a thermometer.

The mass of water, the time, the temperature for each time should be noted and a graph of Temperature versus time should be made

Explanation:

The design of an experiment is to place the beaker in the microwave, with a good amount of water (approximately ⅔ of its capacity) and turn it on for small periods of time, generally the minimum is 30 s, quickly open the microwave, place a thermometer or better yet an infrared thermometer to measure the temperature of the water; repeat this several times.

The advantage of the infrared thermometer is that it reduces the transfer of heat between the water and the thermometer.

The mass of water, the time, the temperature for each time should be noted and a graph of Temperature versus time should be made.

The equipment to use is: a beaker, a fixed amount of water, a thermometer.

The main precaution that must be taken is not to open the microwave while it is on.

4 0
3 years ago
Find evidence of three forces around your home
Daniel [21]

Pulling open a door, your weight, and a magnet on your refrigerator

7 0
3 years ago
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