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3 years ago

11

A 2-ft-high and 5-ft-wide rectangular plate is submerged vertically in the water so that the top is 1 ft below the surface. Expr

ess the hydrostatic force against one side of the plate as an integral.

1 answer:

kondaur [170]3 years ago

8 0

Answer:

63393.8 lbfeet/sec^2

Explanation:

Recall that the weight density of water is 62.5 lb/ft3

F = PA P = hρg = h x 62.5 x 32.2 A = 5 x dh force= integral of (hρg3 x dy) // 3 is width of plane force= integral of ( 62.5 x 32.2 x 3 x hdh) from 2 to 5 force= 62.5 x 32.2 x 3 x (5^2-2^2)/2 = 63393.8 lbfeet/sec^2

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50 grams of ice cubes at -15°C are used to chill a water at 30°C with mass mH20 = 200 g. Assume that the water is kept in a foam

Arada [10]

Answer : The final temperature is, $25.0^oC$

Explanation :

In this problem we assumed that heat given by the hot body is equal to the heat taken by the cold body.

$q_1=-q_2$

$m_1\times c_1\times (T_f-T_1)=-m_2\times c_2\times (T_f-T_2)$

where,

$c_1$ = specific heat of ice = $2.09J/g^oC$

$c_2$ = specific heat of water = $4.18J/g^oC$

$m_1$ = mass of ice = 50 g

$m_2$ = mass of water = 200 g

$T_f$ = final temperature = ?

$T_1$ = initial temperature of ice = $-15^oC$

$T_2$ = initial temperature of water = $30^oC$

Now put all the given values in the above formula, we get:

$50g\times 2.09J/g^oC\times (T_f-(-15))^oC=-200g\times 4.184J/g^oC\times (T_f-30)^oC$

$T_f=25.0^oC$

Therefore, the final temperature is, $25.0^oC$

5 0

3 years ago

The elastic energy stored in your tendons can contribute up to 35 % of your energy needs when running. Sports scientists have st

irina [24]

Complete Question:

The elastic energy stored in your tendons can contribute up to 35 % of your energy needs when running. Sports scientists have studied the change in length of the knee extensor tendon in sprinters and nonathletes. They find (on average) that the sprinters' tendons stretch 43 mm , while nonathletes' stretch only 32 mm . The spring constant for the tendon is the same for both groups, $31 {\rm {N}/{mm}}$ . What is the difference in maximum stored energy between the sprinters and the nonathlethes?

Answer:

$\triangle E = 12.79 J$

Explanation:

Sprinters' tendons stretch, $x_s = 43 mm = 0.043 m$

Non athletes' stretch, $x_n = 32 mm = 0.032 m$

Spring constant for the two groups, k = 31 N/mm = 3100 N/m

Maximum Energy stored in the sprinter, $E_s = 0.5kx_s^2$

Maximum energy stored in the non athletes, $E_m = 0.5kx_n^2$

Difference in maximum stored energy between the sprinters and the non-athlethes:

$\triangle E = E_s - E_n = 0.5k(x_s^2 - x_n^2)\\\triangle E = 0.5*3100* (0.043^2 - 0.032^2)\\\triangle E = 0.5*31000*0.000825\\\triangle E = 12.79 J$

4 0

3 years ago

So this helicopter pilot dropped me in the middle of an absolutely smooth frictionless

Llana [10]

Dang dude you are a soldier! Good job

5 0

3 years ago

Read 2 more answers

Suppose you are standing on the edge of a dock and jump straight down. If you land on sand your stopping time is much shorter th

denis-greek [22]

Answer:

In bringing you to a halt, the sand and the water exert the same impulse on you, but the sand exerts a greater average force

Explanation:

7 0

3 years ago

A small airplane flies 780 miles with an average speed of 260 miles per hour. 1.5 hours after the plane leaves, a Boeing 747 lea

Lera25 [3.4K]

Answer:

520 miles per hour

Explanation:

Let the speed of the Boeing 747 be x miles per hour.

The small airplane covers distance of 780 miles with speed 260 miles per hour.

Also,

After 1.5 hours the Boeing 747 leave the same place and reaches at same time. Both covered distance of 780 miles.

So,

<u>Time taken by Boeing 747 + 1.5 hours = Time taken by small plane.</u>

Also,

Time = Distance/ speed

So,

780 / x + 1.5 = 780/ 260

Solving for x, we get:

<u>x = 520 miles per hour</u>

6 0

3 years ago