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Murrr4er [49]
3 years ago
13

A concrete highway is built of slabs 18.0 m long (at 25 °C). How wide should the expansion cracks be (at 25 °C) between the slab

s to prevent buckling if the annual extreme temperatures are −32 °C and 52 °C?(the coefficient of linear expansion of concrete is 1.20 × 10 − 5 °C-1) g
Physics
1 answer:
yulyashka [42]3 years ago
7 0

To solve the problem it is necessary to apply the concepts related to thermal expansion of solids. Thermodynamically the expansion is given by

\Delta L = L_0 \alpha \Delta T

Where,

L_0 = Original Length of the bar

\Delta T= Change in temperature

\alpha= Coefficient of thermal expansion

On the other hand our values are given as,

L_0 = 18m

\alpha = 12*10^{-6}/\°C

T_2 = 52\°C

T_1= 25\°C

Replacing we have,

\Delta L = L_0 \alpha (T_2-T_1)

\Delta L = (18)(12*10^{-6})(52-25)

\Delta L = 5.832*10^{-3}m

The width of the expansion of the cracks between the slabs is 0.5832cm

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he measured flow rate of water through a 20 mm diameter pipe is 75 L/min. What is the average velocity (in m/s) of water flowing
Masteriza [31]

Answer:

Average velocity of water flow through the pipe = 3.98 m/s

Explanation:

Diameter of pipe = 20 mm

Discharge = 75 L/min

We know that

        Discharge = Area x Velocity

      \texttt{Area of pipe}=\frac{\pi d^2}{4}=\frac{\pi \times (20\times 10^{-3})^2}{4}=3.14\times 10^{-4}m^2

       Discharge = 75 L/min

                         =\frac{75\times 10^{-3}}{60}=1.25\times 10^{-3}m^3/s

Substituting

        1.25\times 10^{-3}=3.14\times 10^{-4}\times V\\\\V=3.98m/s

Average velocity of water flow through the pipe = 3.98 m/s

6 0
3 years ago
Based on Nia's notes, what would be the BEST way to investigate the heat transfer based on the movement of the molecules?
allochka39001 [22]

Answer: Nia could measure the temperature of the bottom floor of a house to see if the heat had risen in the house due to convection.

Explanation:

5 0
3 years ago
Read 2 more answers
A speed-time graph shows a car moving at 10 m/s for 10 s. The cars speed constantly decreases until it comes to a stop at 30 s.
Ray Of Light [21]

speed of the car at t = 10 s is given as 10 m/s

now at t = 30 s car comes to rest so v = 0

now in this velocity time graph we can say slope will show the acceleration of the car as we know that acceleration is rate of change in velocity

a = \frac{v_f - v_i}{\Delta t}

as we know that

v_f = 0

v_i = 10 m/s

\Delta t = (30 - 10) = 20 s

now from above formula

a = \frac{0 - 10}{20} = -0.5 m/s^2

So slope of the graph will represent the acceleration of car which is 0.5 m/s^2

5 0
3 years ago
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In the Bathburst 1000, racing cars take 6.25 hours to complete the 1000km race. Race is their average speed?
balandron [24]

Answer:

160

Explanation:

1000 divided by 6.25

3 0
3 years ago
a stone is thrown horizonttaly from a cliff of a hill with an initial velocity of 30m/s it hits the ground at a horizontal dista
ELEN [110]

Answer:

a) Time = 2.67 s

b) Height = 35.0 m

Explanation:

a) The time of flight can be found using the following equation:

x_{f} = x_{0} + v_{0_{x}}t + \frac{1}{2}at^{2}   (1)

Where:

x_{f}: is the final position in the horizontal direction = 80 m

x_{0}: is the initial position in the horizontal direction = 0

v_{0_{x}}: is the initial velocity in the horizontal direction = 30 m/s

a: is the acceleration in the horizontal direction = 0 (the stone is only accelerated by gravity)

t: is the time =?  

By entering the above values into equation (1) and solving for "t", we can find the time of flight of the stone:  

t = \frac{x_{f}}{v_{0}} = \frac{80 m}{30 m/s} = 2.67 s

b) The height of the hill is given by:

y_{f} = y_{0} + v_{0_{y}}t - \frac{1}{2}gt^{2}

Where:

y_{f}: is the final position in the vertical direction = 0

y_{0}: is the initial position in the vertical direction =?

v_{0_{y}}: is the initial velocity in the vertical direction =0 (the stone is thrown horizontally)            

g: is the acceleration due to gravity = 9.81 m/s²

Hence, the height of the hill is:

y_{0} = \frac{1}{2}gt^{2} = \frac{1}{2}9.81 m/s^{2}*(2.67 s)^{2} = 35.0 m  

I hope it helps you!

5 0
3 years ago
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