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Elanso [62]
3 years ago
6

If mechanical energy is conserved, then a pendulum that has a potential energy of 20 J at its highest point and 0.5 J at its low

est point has _____ as its kinetic energy at its lowest point.
20 J
0.5 J
19.5 J
20.5 J
Physics
1 answer:
liraira [26]3 years ago
4 0
At the highest point: kinetic energy is 0 due to the speed  is 0

So the total mechanical energy is 20

Assume no frictions present, then the mechanical energy is conserved

So at the lowest point, kinetic energy = mechanical energy - potential energy

Answer will be 20 - 0.5 = 19.5 J
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(8 points) Air is used as the working fluid in a simple ideal Brayton cycle that has a pressure ratio of 12, a compressor inlet
trapecia [35]

Answer:

a ) \dot m = 351.49 kg/s

b)  \dot m_{actual} = 1046.15 kg/s

Explanation:

given data:

pressure ration rp = 12

inlet temperature = 300 K

TURBINE inlet temperature  = 1000 K

AT the end of isentropic process (compression) temperature is

\frac{T_2'}{T_1} = rp ^{\frac{\gamma -1}{\gamma}}

\frac{T_2'}{300} = 12^{\frac{1.4 -1}{1.4}}

T_2' = 610.181 K

AT the end of isentropic process (expansion) temperature is

\frac{T_3}{T_4'} = rp ^{\frac{\gamma -1}{\gamma}}

\frac{1000'}{T_4'} = 12^{\frac{1.4 -1}{1.4}}

T_4' = 491.66 K

isentropic work is given as

w(compressor) = CP (T_2' -T_1)

w = 1.005(610.18 - 300)

w = 311.73 kJ/kg

w(turbine) = 1.005( 1000 - 491.66)

w(turbine) = 510.88 kJ/kg

a) mass flow rate for isentropic process is given as

\dot m = \frac{70000}{510.88 - 311.73}

\dot m = 351.49 kg/s

b) actual mass flow rate uis given as

\dot m_{actual} = \frac{70000}{51.088\times 0.85 - \frac{311.73}{0.85}}

\dot m_{actual} = 1046.15 kg/s

6 0
3 years ago
An elevator accelerates upward at 2.0 m/s?,
amm1812

Answer:

Force the floor exerts on the  passenger is 833 N.

Explanation:

  • Weight of passenger (F_{g}) = mg = 85 × 9.8 N = 833 N
  • Force the floor exerts on the  passenger (F_{N}) = ?
  • For the elevator with the speed as 2.0 m/s the net force is zero, it means that the force is balanced.

                                       i.e. F_{N} = - F_{g} = -mg = 833 N

                                       hence  F_{N} is 833 N

  • If the lift was not at a constant speed i.e. if it had acceleration (m/s^{2})  then the case would be different.

4 0
2 years ago
Cations have fewer _____ than _____.
FrozenT [24]
Cations are positively charged ions. And for positive charged ions, it means the positive charges, protons, are more than the negative charges, the electrons.

Therefore Cations have fewer electrons than protons.

So the answer is:    c. electrons; protons. 
3 0
3 years ago
Read 2 more answers
A spaceship moves radially away from Earth with acceleration 29.4 m/s 2 (about 3g). How much time does it take for sodium street
Gemiola [76]

Answer:

doppler shift's formula for source and receiver moving away from each other:

<em>λ'=λ°√(1+β/1-β)</em>

Explanation:

acceleration of spaceship=α=29.4m/s²

wavelength of sodium lamp=λ°=589nm

as the spaceship is moving away from earth so wavelength of earth should increase w.r.t increasing speed until it vanishes at λ'=700nm

using doppler shift's formula:

<em>λ'=λ°√(1+β/1-β)</em>

putting the values:

700nm=589nm√(1+β/1-β)

after simplifying:

<em>β=0.17</em>

by this we can say that speed at that time is: v=0.17c

to calculate velocity at an acceleration of a=29.4m/s²

we suppose that spaceship started from rest so,

<em>v=v₀+at</em>

where v₀=0

so<em> v=at</em>

as we want to calculate t so:-

<em>t=v/a</em>                                                v=0.17c      ,c=3x10⁸           ,a=29.4m/s²

putting values:

=0.17(3x10⁸m/s)/29.4m/s²

<em>t=1.73x10⁶</em>

7 0
3 years ago
When a funnel shaped cloud considered as a tornado?
gladu [14]
It has to be one continuous column of cloud (air) connected to the ground and in constant rotation.
3 0
2 years ago
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