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Mashcka [7]
3 years ago
7

Sam is moving house and is carrying a 300N box of books up a flight of steps 5m high, it takes her 30 seconds. Gary follows her

carrying a bag of clothes doing 1000 J of work; it only takes him 25 seconds. Who provides the biggest power? Show your working.
Physics
1 answer:
ioda3 years ago
7 0

Answer: Sam provides the biggest power

Explanation: <u>Power</u> is defined, in Physics, as the rate of work done. <u>Work</u> is energy transferred to an object due to the force causing the displacement of the object.

So, to determine Power:

For Sam:

P = \frac{work}{time}

P=\frac{F.d}{t}

P=\frac{300.5}{30}

P = 50 Watts

The unit for Power is [P] = J/s = Watt

For Gary:

P = \frac{work}{time}

P=\frac{1000}{25}

P = 40 Watts

Comparing power of Sam and Gary, we can conclude that Sam provides the biggest power of 50 Watts.

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An object of irregular shape has a characteristic length of L = 0.5 m and is maintained at a uniform surface temperature of Ts =
goblinko [34]

Answer:

The value of the average convection coefficient is 20 W/Km².

Explanation:

Given that,

For first object,

Characteristic length = 0.5 m

Surface temperature = 400 K

Atmospheric temperature = 300 K

Velocity = 25 m/s

Air velocity = 5 m/s

Characteristic length of second object = 2.5 m

We have same shape and density of both objects so the reynold number will be same,

We need to calculate the value of the average convection coefficient

Using formula of  reynold number for both objects

R_{1}=R_{2}

\dfrac{u_{1}L_{1}}{\eta_{1}}=\dfrac{u_{2}L_{2}}{\eta_{2}}

\dfrac{h_{1}L_{1}}{k_{1}}=\dfrac{h_{2}L_{2}}{k_{2}}

Here, k_{1}=k_{2}

h_{2}=h_{1}\times\dfrac{L_{1}}{L_{2}}

h_{2}=\dfrac{q}{T_{2}-T_{1}}\times\dfrac{L_{1}}{L_{2}}

Put the value into the formula

h_{2}=\dfrac{10000}{400-300}\times\dfrac{0.5}{2.5}

h_{2}=20\ W/Km^2

Hence, The value of the average convection coefficient is 20 W/Km².

7 0
4 years ago
At t = 0 the components of a radio-controlled car's velocity are vx = 0.5 m/s and vy = 1.2 m/s. Find the components of the car's
FinnZ [79.3K]

Answer:

x-component of velocity = 5.7 m/s

y-component of velocity = -1.4 m/s          

Explanation:

Use first equation of motion to find components of velocity at a given time:

v = u + at

where, v is  the final velocity, u is the initial velocity, a is the acceleration and t is the time.

Given:

u_x= 0.5 m/s\\u_y=1.2 m/s\\a_x=2 m/s^2\\a_y=-1m/s^2\\t = (2.6-0)s =2.6 s

v_x=u_x+a_xt\\\Rightarrow v_x=0.5+2\times 2.6\\\Rightarrow v_x=5.7 m/s

v_y=u_y+a_yt\\\Rightarrow v_y=1.2-1\times 2.6\\\Rightarrow v_y=-1.4 m/s

5 0
3 years ago
PLEASE HELP ASAP!!! CORRECT ANSWER ONLY PLEASE!!! I CANNOT RETAKE THIS AND I NEED ALL CORRECT ANSWERS ONLY!!!
Dominik [7]

the purpose of fuses and circuit breakers is (first answer)

7 0
3 years ago
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a glass beaker has a mass of 50g. a liquid of density 1.8g/cm3 is poured into the beaker until it reaches the 200cm3 mark. calcu
xz_007 [3.2K]

<u>Answer:</u>

total mass = 410 g

<u>Explanation:</u>

density = 1.8 g/cm³

volume = 200 cm³

                              density = mass / volume

                              mass (of liquid) = density   x    volume

                                        = 1.8 x 200

                                        = 360 g

          total mass (beaker + liquid) = 50 + 360 = 410 g     [Ans]

Hope this helps!

5 0
3 years ago
Dr. james van allen and his group of united states scientists discovered a set of ___________. magnetic equators planets magneti
Fofino [41]

RADIATION BELTS....... I think but it should be radiation belt

3 0
3 years ago
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