A car moves with constant speed and then constant acceleration

An opera singer in a convertible sings a note at 600 Hz while cruising down the highway at 90km/hr. What is the frequency heard

Inessa05 [86]

Answer:

$f=647.17Hz$

Explanation:

Given data

Frequency fs=600 Hz

Velocity Vs=90 km/hr =25 m/s

Speed of sound v=343 m/s

To find

Frequency f heard by a person standing beside the road in front of the car

Solution

From Doppler's effect we know that:

$f=f_{s}(\frac{v+vL}{v+vs} )\\ as\\vL=0$

Here Vs is negative as the source is moving towards listener

$f=fs(\frac{v+0}{v-vs} )\\f=(600Hz)(\frac{343m/s+0}{343m/s-25m/s} )\\f=647.17Hz$

5 0

4 years ago

A group of students left school at 8:00 am on a field trip to a science museum 90 miles away. Which best describes the average s

Aliun [14]

Answer:

45

Explanation:

because the equation for speed is distance divided by time! hope that helps gave a nice day!

7 0

3 years ago

A 3-ft3 rigid tank initially contains saturated water vapor at 300°F. The tank is connected by a valve to a supply line that car

zhannawk [14.2K]

Explanation:

$Given\\V=3ft^3\\T_{1} =300^oF\\T_{L} =400^oF\\P_{L} =200psia\\V_{f} =0.5V$

We assume kinetic and potential energy changes are negligible and there is no work interactions.

a) Taking tank as a system, The energy balance can be define as

$E_{in}- E_{out}= E_{sys}$

$m_{i} h_{L} -Q_{out}=m_{2} u_{2}-m_{1} u_{1}$

The mass balance could be written as

$m_{in}- m_{out}= m_{sys} \\m_{i}= m_{2}- m_{1}$

The final pressure in the tank could be defined as following

$P_{2} =P_{sat300^oF}$

from standard steam table we know at

$T_{2}= T_{1}=300^oF\\ P_{2}=67.028psia$

b)

From steam table at

$T_{1} =300^oF\\v_{1}= v_{g}=6.4663ft^3/lbm\\v_{1}= v_{g}=1099.8Btu/lbm\\ v_{f} =0.01745ft^3/lbm\\v_{f} =269.51Btu/lbm\\$

$at\\P_{L} =200psia\\T_{L}=400^oF\\h_{L}=1210.9Btu/lbm$

initial mass in the tank could be define as

$m_{1}=\frac{V}{v_{1} } \\m_{1} =\frac{3}{6.4663} =0.464lbm\\$

Final mass in the tank could be define as

$m_{2}=\frac{V_{f} }{v_{f} }+\frac{V_{g} }{v_{g} } \\ m_{2} =\frac{1.5}{0.01745} +\frac{1.5}{6.4663} =86.2lbm$

The amount of steam that has entered the tank

$m_{i}=m_{2}- m_{1}\\ m_{i}=86.2-0.464=85.74lbm$

c)

The internal energy in final state could be defined as following

$U_{2}=m_{f} u_{f}+ m_{g} u_{g}\\ U_{2} =85.96*269.51+0.232*1099.8=23422Btu\\$

The heat transfer could be defined as following

$Q_{out}=m_{i} h_{L}+m_{1} u_{1}-m_{2} u_{2}\\ Q_{out}=85.74*1210.9+0.464*1099.8-23422=80910Btu$

6 0

3 years ago

Read 2 more answers

Calculate the calories lost when 95 g of water cools from 45 ∘C to 29 ∘C. Express your answer to two significant figures and inc

lubasha [3.4K]

Answer:

1,520.00 calories

Explanation:

Water molecules are linked by hydrogen bonds that require a lot of heat (energy) to break, which is released when the temperature drops. That energy is called specific heat or thermal capacity (ĉ) when it is enough to change the temperature of 1g of the substance (in this case water) by 1°C. Water ĉ equals 1 cal/(g.°C).

Given that ĉ = Q / (m.ΔT),

where Q= calories transferred between the system and its environment or another system (unity: calorie or cal) (what we are trying to find out),

m= mass of the substance (unity: grams or g), and

ΔT= difference of temperature (unity: Celsius degrees or °C); and

m= 95g and ΔT= 16°C:

Q= 1 cal/(g.°C).95g.16°C = 1,520.00 cal

8 0

4 years ago

For a certain interval of time, an object is acted on by a constant non-zero force. Which of the following statements is true fo

aleksklad [387]

For a certain interval of time, an object is acted on by a constant non-zero force. For this interval of time . . . . .

A. The object is at rest. No. From F=ma, if F is not zero, the object can't remain at rest.

B. The object's velocity changes. Yes. From F=ma, if F is not zero, there must be acceleration.

C. The object's velocity can only increase. No. It might decrease.

D. The object is moving with constant velocity. No. From F=ma, if F is not zero, there must be acceleration.

E. The object is accelerating. Yes. From F=ma, if F is not zero, there must be acceleration.

8 0

4 years ago

Read 2 more answers