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3 years ago

5

The temperature of a plastic cube is monitored while the cube is pushed 1.8 m across a floor at constant speed by a horizontal f

orce of 24 N. The monitoring reveals that the thermal energy of the cube increases by 18 J. What is the increase in the thermal energy of the floor along which the cube slides?

1 answer:

algol133 years ago

8 0

Answer: 25.2 Joules

Explanation:

Work = total heat energy = Fs = (24)(1.8) = 43.2 J

Heat = cube + floor = 43.2J

floor = 43.2 J - 18 J = 25.2 J

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Running is probably the simplest individual sport for promoting both health-related and skill-related fitness.

Tamiku [17]

Answer:

Running is probably the simplest individual sport for promoting both health-related and skill-related fitness. Fencing is often referred to as "mental chess" because it requires dexterity, endurance, and discipline. Individual sports require the coach to make all of the decisions for the athlete.

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2 years ago

a foul ball is hit into the stands at a baseball game. the ball rises to a height of 38 meters and is caught on its way down by

lisov135 [29]

The velocity of the ball when it was caught is 12.52 m/s.

<em>"Your question is not complete it seems to be missing the following, information"</em>,

find the velocity of the ball when it was caught.

The given parameters;

maximum height above the ground reached by the ball, H = 38 m

height above the ground where the ball was caught, h = 30 m

The height traveled by the ball when it was caught is calculated as follows;

y = H - h

y = 38 - 30 = 8 m

The velocity of the ball when it was caught is calculated as;

$v_f^2 = v_0 + 2gh\\\\v_f^2 = 0 + (2\times 9.8 \times 8)\\\\v_f^2 = 156.8\\\\v_f = \sqrt{156.8} \\\\v_f = 12.52 \ m/s$

Thus, the velocity of the ball when it was caught is 12.52 m/s.

Learn more here: brainly.com/question/14582703

4 0

3 years ago

1) A car accelerates uniformly from rest and reaches a speed of 19.8 m/s in 7 s. The diameter of a tire is 38.5 cm. Find the num

andre [41]

Answer:

1) 57 revolutions.

2) 4.52 m

3) 1531.2 m

Explanation:

Question 1:

Given:

Initial velocity, $u = 0$

Final velocity, $v = 19.8\ m/s$

Time, $t = 7\ s$

Acceleration, $a = \frac{\textrm{Final velocity-Initial velocity}}{Time}=\frac{19.8}{7}=2.83\ m/s^2$

Now, displacement of the tire is given as:

$S=ut+\frac{a}{2}t^2\\S=0+\frac{2.83}{2}7^2=69.335\ m$

Displacement of tire in 1 revolution is equal to its circumference.

Therefore, displacement in 1 revolution = $\pi\times(Diameter)=\pi \times 38.5\times 10^{-2}=1.2095\ m$

Now, number of revolutions is given as:

$N=\frac{Total\ displacement}{Displacement\ per\ revolution}\\N=\frac{69.335}{1.2095}=57$

Therefore, the number of revolutions are 57.

Question 2:

Given:

Radius of the wheel is, $R=4.8\ m$

Angle of rotation is, $\theta=54$ °

Converting degree to radians, we get:

$\theta=54\times \frac{\pi}{180}=0.3\pi$

Now, path length is given as:

$L=R\theta=(4.8)(0.3\pi)=1531.2\ m$

Therefore, the path length of a point on the wheel is 4.52 m

Question 3:

Radius of the wheel is, $R=4.8\ m$

Angle of rotation is, $\theta=319$ radians

Now, path length is given as:

$L=R\theta=(4.8)(319)=4.52\ m$

Therefore, the path length of a point on the wheel is 1531.2 m.

7 0

3 years ago

How are cactus adapted to survive in deserts?

andreev551 [17]

1. They have evolved their leaves into spikes for minimum water loss through transpiration.

2. They have a waxy layer for minimum water loss.

3. They have thick walls for minimum water loss.

4. They can take water from atmosphere.

5. They change the photo energy from Sun into an intermediate stage and store it, so that they can make food even in night.

7 0

3 years ago

A ball is thrown into the air by a baby alien on a planet in the system of Alpha Centauri with a velocity of 35 ft/s. Its height

Svetllana [295]

Answer:

Part A:

(a): -121.26 ft/s.

(b): -121.13 ft/s.

(c): -121.052 ft/s.

(d): -121.026 ft/s.

Part B:

-121.00 ft/s.

Explanation:

Given that the height of the balloon after t seconds is

$\rm y(t) = 35 t-26t^2.$

The average velocity of an object is defined as the total distance traveled by the object divided by the time taken in covering that distance.

$\rm v_{av} = \dfrac{y_2-y_1}{t_2-t_1}$

where,

$\rm y_2,\ y_1$ are the positions of the object at time $\rm t_1$ and $\rm t_2$ respectively.

<h2><u>Part A:</u></h2><h2 />

For the average velocity for the time period beginning when t=3 and lasting .01 sec.

For this case,

$\rm t_1 = 3\ sec.\\t_2 = 3+0.01\ sec = 3.01\ sec.\\\\Therefore, \\\\y_1 = 35\cdot 3-26\cdot 3^2=-129\ ft.\\y_2 = 35\cdot 3.01-26\cdot 3.01^2=-130.2126\ ft.\\\\\Rightarrow v_{av}=\dfrac{-130.2126-(-129)}{3.01-3}=-121.26\ ft/s.$

For the average velocity for the time period beginning when t=3 and lasting .005 sec.

For this case,

$\rm t_1 = 3\ sec.\\t_2 = 3+0.005\ sec = 3.005\ sec.\\\\Therefore, \\\\y_1 = 35\cdot 3-26\cdot 3^2=-129\ ft.\\y_2 = 35\cdot 3.005-26\cdot 3.005^2=-129.60565\ ft.\\\\\Rightarrow v_{av}=\dfrac{-129.60565-(-129)}{3.005-3}=-121.13\ ft/s.$

For the average velocity for the time period beginning when t=3 and lasting .002 sec.

For this case,

$\rm t_1 = 3\ sec.\\t_2 = 3+0.002\ sec = 3.002\ sec.\\\\Therefore, \\\\y_1 = 35\cdot 3-26\cdot 3^2=-129\ ft.\\y_2 = 35\cdot 3.002-26\cdot 3.002^2=-129.2421\ ft.\\\\\Rightarrow v_{av}=\dfrac{-129.2421-(-129)}{3.002-3}=-121.052\ ft/s.$

For the average velocity for the time period beginning when t=3 and lasting .001 sec.

For this case,

$\rm t_1 = 3\ sec.\\t_2 = 3+0.001\ sec = 3.001\ sec.\\\\Therefore, \\\\y_1 = 35\cdot 3-26\cdot 3^2=-129\ ft.\\y_2 = 35\cdot 3.001-26\cdot 3.001^2=-129.121\ ft.\\\\\Rightarrow v_{av}=\dfrac{-129.121-(-129)}{3.001-3}=-121.026\ ft/s.$

<h2><u>Part B:</u></h2>

The instantaneous velocity of the balloon at the given time is defined as the rate of change of its position at that time.

$\rm v(t) = \dfrac{dy}{dt}\\=\dfrac{d}{dt}\left ( 35 t-26t^2\right )\\\\=35-26\times 2t.\\\\At\ t=3,\\\\v(t)=35-26\times 2\times 3=-121.00\ ft/s.$

<u>Note:</u><em> The negative sign with all the velocities indicates that the direction of these velocities are downwards.</em>

<em> </em>

8 0

4 years ago