All categories

3 years ago

A colony of troglodytes has been in a lengthy feud with

Physics

1 answer:

Troyanec [42]3 years ago

7 0

Answer:

h = 181.73 m

Explanation:

given,

distance between the neighbors = 42 m

speed of the rock rolling = 6.9 m/s

vertical velocity of ball = 0 m/s

height of the cliff = ?

time taken by the ball to travel 42 m

d = s x t

s is the horizontal speed of the ball equal to 6.9 m/s

$t =\dfrac{d}{s}$

$t =\dfrac{42}{6.9}$

t = 6.09 s

same time will be taken by the ball to travel vertical distance

Using equation of motion

$h = u t + \dfrac{1}{2}gt^2$

$h = 0+ \dfrac{1}{2}gt^2$

$h = \dfrac{1}{2}\times 9.8 \times 6.09^2$

h = 181.73 m

You might be interested in

Air at 3 104 kg/s and 27 C enters a rectangular duct that is 1m long and 4mm 16 mm on a side. A uniform heat flux of 600 W/m2 is

ad-work [718]

Answer:

$T_{out}=27.0000077$ ºC

Explanation:

First, let's write the energy balance over the duct:

$H_{out}=H_{in}+Q$

It says that the energy that goes out from the duct (which is in enthalpy of the mass flow) must be equals to the energy that enters in the same way plus the heat that is added to the air. Decompose the enthalpies to the mass flow and specific enthalpies:

$m*h_{out}=m*h_{in}+Q\\m*(h_{out}-h_{in})=Q$

The enthalpy change can be calculated as Cp multiplied by the difference of temperature because it is supposed that the pressure drop is not significant.

$m*Cp(T_{out}-T_{in})=Q$

So, let's isolate $T_{out}$ :

$T_{out}-T_{in}=\frac{Q}{m*Cp}\\T_{out}=T_{in}+\frac{Q}{m*Cp}$

The Cp of the air at 27ºC is 1007 $\frac{J}{kgK}$ (Taken from Keenan, Chao, Keyes, “Gas Tables”, Wiley, 1985.); and the only two unknown are $T_{out}$ and Q.

Q can be found knowing that the heat flux is 600W/m2, which is a rate of heat to transfer area; so if we know the transfer area, we could know the heat added.

The heat transfer area is the inner surface area of the duct, which can be found as the perimeter of the cross section multiplied by the length of the duct:

Perimeter:

$P=2*H+2*A=2*0.004m+2*0.016m=0.04m$

Surface area:

$A=P*L=0.04m*1m=0.04m^2$

Then, the heat Q is:

$600\frac{W}{m^2} *0.04m^2=24W$

Finally, find the exit temperature:

$T_{out}=T_{in}+\frac{Q}{m*Cp}\\T_{out}=27+\frac{24W}{3104\frac{kg}{s} *1007\frac{J}{kgK} }\\T_{out}=27.0000077$

$T_{out}$ =27.0000077 ºC

The temperature change so little because:

The mass flow is so big compared to the heat flux.
The transfer area is so little, a bigger length would be required.

3 0

3 years ago

The brakes on a truck fail as it approaches a car stopped at a red light. Use Newton’s first and second law of motion to explain

PolarNik [594]

newtons first law states that a object in motion will stay in motion unless acted on by an outside force and an object at rest will stay at rest for the same reason. the force of a moving object is equal to its mass times its acceleration.

3 0

3 years ago

Read 2 more answers

What is true for ALL of the examples of electromagnetic waves?

nasty-shy [4]

A they all move the same speed in a vacuum this is because in a the photons don't bump in to anything

5 0

3 years ago

A net force of 10.N accelerates an object at 5.0 m/s^2. What net force would be required to accelerate the same object at 1.0 m/

Leokris [45]

Answer:

I believe the answer is 2.0

Explanation:

4 0

3 years ago

How many does the UK have of nuclear power stations

DIA [1.3K]

Answer: 11

Explanation: In addition to nuclear reprocessing units at Sellafield and Urenco's Tails Management Facility (TMF) in Capenhurst, the UK has 11 active nuclear reactors in five locations (10 advanced gas-cooled reactors (AGR) and one pressurised water reactor (PWR)).

Please give brainliest or whatever brainlyest if this has helped :)

7 0

3 years ago