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Artist 52 [7]
3 years ago
15

In moving out of a dormitory at the end of the semester, a student does 1.82 x 104 J of work. In the process, his internal energ

y decreases by 4.07 x 104 J.
Determine each of the following quantities (including the algebraic sign):

(a)W,

(b)U

(c)Q.
Physics
1 answer:
emmainna [20.7K]3 years ago
4 0

Answer:

Explanation:

(a) Work done, W = 1.82 x 10^4 J

(b) internal energy, U = - 4.07 x 10^4 J ( as it decreases)

(c) According to the first law of thermodynamics  

Q = W + U

Q = 1.82 x 10^4 - 4.07 x 10^4

Q = - 2.25 x 10^4 J

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1. A car is traveling at 36 m/s hits a tree and comes to rest in 0.05 seconds.
QveST [7]

Answer: a. -720m/s^2

b. Yes, airbags will deploy

Explanation:

The formula for acceleration is:

= (Final velocity - Initial velocity)/Time

Final velocity = 0m/s

Initial velocity = 36m/s

Time taken = 0.05s

= (Final velocity - Initial velocity)/Time

= (0 - 36)/0.05

= -36/0.05

= -720m/s^2.

Since it's negative, it shows that there was a deceleration.

2. Yes the airbag will deploy since the acceleration gotten is more than -600 m/s^2.

3 0
3 years ago
A 13 kg hanging sculpture is suspended by a 95-cm-long, 5.0 g steel wire. When the wind blows hard, the wire hums at its fundame
Artyom0805 [142]

Answer:

f=81.96 \ Hz

Explanation:

Givens

L=95cm

m_{sculpture} =13kg

m_{wire}=5g

The frequency is defined by

f=\frac{v}{\lambda}

Where v is the speed of the wave in the string and \lambda is its wave length.

The wave length is defined as \lambda = 2L = 2(0.95m)=1.9m

Now, to find the speed, we need the tension of the wire and its linear mass density

v=\sqrt{\frac{T}{\mu} }

Where \mu=\frac{0.005kg}{0.95m}= 5.26 \times 10^{-3} and the tension is defined as T=m_{sculpture} g=13kg(9.81 m/s^{2} )=127.53N

Replacing this value, the speed is

v=\sqrt{\frac{127.53N}{5.26 \times 10^{-3} } }=155.71 m/s

Then, we replace the speed and the wave length in the first equation

f=\frac{v}{\lambda}\\f=\frac{155.71 m/s}{1.9m}\\ f=81.96Hz

Therefore, the frequency is f=81.96 \ Hz

3 0
3 years ago
Read 2 more answers
At this radius, what is the magnitude of the net force that maintains circular motion exerted on the pilot by the seat belts, th
Ainat [17]

Answer:

Fc=5253 N

Explanation:

Answer:

Fc=5253 N

Explanation:

sequel to the question given, this question would have taken precedence:

"The 86.0 kg pilot does not want the centripetal acceleration to exceed 6.23 times free-fall acceleration. a) Find the minimum radius of the plane’s path. Answer in units of m."

so we derive centripetal acceleration first

ac (centripetal acceleration) = v^2/r

make r the subject of the equation

r= v^2/ac

 ac is 6.23*g which is 9.81

v is 101m/s

substituing the parameters into the equation, to get the radius

(101^2)/(6.23*9.81) = 167m

Now for part

( b) there are two forces namely, the centripetal and the weight of the pilot, but the seat is exerting the same force back due to newtons third law.

he net force that maintains circular motion exerted on the pilot by the seat belts, the friction against the seat, and so forth is the centripetal force.

Fc (Centripetal Force) = m*v^2/r  

So (86kg* 101^2)/(167) =

Fc=5253 N

4 0
3 years ago
A magnetic field would be produced by a beam of
kumpel [21]
3 protons should be your answer
4 0
3 years ago
If you have 10.0 g of a substance that decays with a half-life of 14 days, then how much will you have after 42 days?
Nat2105 [25]
The formula for the mass that remains:
m=m_0 \times (\frac{1}{2})^\frac{t}{T}
m₀ - the initial mass, t - time, T - the half-life

m_0=10 \ g \\
T=14 \ d \\
t=42 \ d \\ \\
m=10 \times (\frac{1}{2})^\frac{42}{14}=10 \times (\frac{1}{2})^3=10 \times \frac{1}{8}=10 \times 0.125=1.25

The answer is c. 1.25 g.
6 0
3 years ago
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