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3 years ago

B h combining g two hydrogen atoms ans one oxygen atom for a molecule of water is made from

1 answer:

5 0

The correct answer to this question is this one:

By definition, if a molecule is composed of two hydrogen atoms and one oxygen atom, that molecule is a water.<span> In fact, the structure of water is written as H20, which signifies that two hydrogen (H) atoms and one oxygen (O) atom make up the molecule.</span>

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As thermal energy is added to a sample of water, the kinetic energy of its

Nesterboy [21]

Answer:

Explanation:

3 0

3 years ago

If you dribble a basketball with a frequency of 1.77 Hz, how long does it take for you to complete 12 dribbles?

Licemer1 [7]

<h2>It takes 6.78 seconds to complete 12 dribbles.</h2>

Explanation:

Frequency of dribble = 1.77 Hz

That is

Number of dribbles in 1 second = 1.77

$\texttt{Time taken for 1 dribble = }\frac{1}{1.77}=0.565s$

Now we need to find how long does it take for you to complete 12 dribbles.

Time taken for 12 dribbles = 12 x Time taken for 1 dribble

Time taken for 12 dribbles = 12 x 0.565

Time taken for 12 dribbles = 6.78 seconds

It takes 6.78 seconds to complete 12 dribbles.

8 0

3 years ago

The terminal velocity of a person falling in air depends upon the weight and the area of the person facing the fluid. Find the t

yuradex [85]

Answer: 104.026 m/s=374.49 km/h

Explanation:

When a body or object falls, basically two forces act on it:

1. The force of air friction, also called "drag force" $D$ :

$D={C}_{d}\frac{\rho V^{2} }{2}A$ (1)

Where:

$C_ {d}=0.7$ is the drag coefficient

$\rho=1.21 kg/m^{3}$ is the density of the fluid (air in this case)

$V$ is the velocity

$A=0.17 m^{2}$ is the transversal area of the object

So, this force is proportional to the transversal area of the falling element and to the square of the velocity.

2. Its weight due to the gravity force $W$ :

$W=m.g$ (2)

Where:

$m=79.5 kg$ is the mass of the object

$g=9.8 m/s^{2}$ is the acceleration due gravity

<h3>So, at the moment when the drag force equals the gravity force, the object will have its terminal velocity: </h3>

$D=W$ (3)

${C}_{d}\frac{\rho V^{2} }{2}A=m.g$ (4)

$V=\sqrt{\frac{2m.g}{\rho A{C}_{d}}}$ (5) This is the terminal velocity

Substituting the known values in (5):

$V=\sqrt{\frac{2(79.5 kg)(9.8 m/s^{2})}{(1.21 kg/m^{3})(0.17m^{2}){(0.7)}}$ (6)

Then:

$V=104.026 m/s$ This is the final velocity in meters per second

Now, let's find the final velocity in kilometers per hour, knowing $1 km=1000 m$ and $1 h=3600 s$ :

$V=104.026 \frac{m}{s} (\frac{1 km}{1000 m})(\frac{3600 s}{1 h})=374.49 km/h$ This is the final velocity in kilometers per hour.

4 0

3 years ago

PRACTICE ANOTHER A cube of wood having an edge dimension of 19.7 cm and a density of 647 kg/m3 floats on water. (a) What is the

dedylja [7]

CHECK COMPLETE QUESTION

The cube of wood having an edge dimension of 19.7cm and a density of 647kg/m3 floats on water

(a) What is the distance from the horizontal top surface of the cube to the water level answer in cm

(b) What mass of lead should be placed on the cube so that the top of the cube will be just level with the water surface answer in kg

Answer:

a)6.29cm

b)2.78 kg

Explanation:

Given:

Let us calculate the volume first, we were given dimension as 19.7cm=0.197m

Volume is (0.197 meters)³ = 0.00764m³

Then we can calculate the mass as;

Given mass is 647 kg/m³ x 0.00774m³ = 4.947kg

The weight = mass × acceleration due to gravity

weight = 4.947 x 9.8 N/kg = 48.44N

By Floating we can say the the buoyancy force has to equal the weight (48.44 N) which has

which is equal to the weight of volume of the displaced water. Or the mass, the calculation is the same.

We know that density of fresh water at 20ºC is 998 kg/m³

Then we can calculate the volume of displaced water as

4.947 kg / 998 kg/m³ = 0.00496 m³

We know that the displaced water has a shape of a rectangular solid with 0.197 meters on the two horizontal dimensions, and h as the height to the surface then

V = 0.197²h = 0.00496

0.00496= 0.197²h

h = 0.1278 meters or 12.78 cm

Then the the distance exposed, would be 19.7–12.78 = 6.29 cm

b) ifthe cube is fully submerged, the volume of the displaced water is 0.00774m³

mass of displaced water is 0.00774m³ x 998 kg/m³ = 7.724 kg

Added mass is the mass of the displaced water – mass of block

= 7.724–4.947 = 2.78 kg

5 0

3 years ago

Two 2.3 kg bodies, A and B, collide. The velocities before the collision are and . After the collision, . What are (a) the x-com

myrzilka [38]

Missing details in the question:

The velocities before collision are

$u_A=(40i+49j) m/s$

$u_B=(35i+11j) m/s$

After the collision:

$v_A=(14i+21j) m/s$

(a) 61 m/s

We can solve the problem by simply treating separately the x- and the y-components of the motion.

Here we want to analzye the motion along x. We have:

$u_A = 40 m/s$ is the initial velocity of A along the x-direction

$u_B = 35 m/s$ is the initial velocity of B along the x-direction

$v_A = 14 m/s$ is the final velocity of A along the x-direction

$v_B = ?$ is the final velocity of B along the x-direction

Since the total momentum along the x-direction must be conserved, we can write

$mu_A + mu_B = mv_A + mv_B$

where

m = 2.3 kg is the mass of the two bodies. Since the mass is the same, we can eliminate it from the equation,

$u_A + u_B = v_A + v_B$

And so, we find the final velocity of B along the x-direction:

$v_B = u_A + u_B - v_A=40+35-14=61 m/s$

(b) 39 m/s

Similarly to what we did in part a), here we analyze the conservation of momentum along the y-direction.

We have:

$u_A = 49 m/s$ is the initial velocity of A along the y-direction

$u_B = 11 m/s$ is the initial velocity of B along the y-direction

$v_A = 21 m/s$ is the final velocity of A along the y-direction

$v_B = ?$ is the final velocity of B along the y-direction

Since the total momentum along the y-direction must be conserved, we can write

$mu_A + mu_B = mv_A + mv_B$

Since the mass is the same, we can eliminate it from the equation,

$u_A + u_B = v_A + v_B$

And so, we find the final velocity of B along the y-direction:

$v_B = u_A + u_B - v_A=49+11-21=39 m/s$

c) +615 J

Here we have to find the total kinetic energy before and after the collision first.

First, we have to find the speed of each object before and after the collision. We have:

$u_A = \sqrt{40^2+49^2}=63.2 m/s\\u_B = \sqrt{35^2+11^2}=36.7 m/s\\v_A = \sqrt{14^2+21^2}=25.2 m/s\\v_B = \sqrt{61^2+39^2}=72.4 m/s$

So, the total kinetic energy before the collision was

$K_i = \frac{1}{2}mu_A^2+\frac{1}{2}mu_B^2 = \frac{1}{2}(2.3)(63.2)^2+\frac{1}{2}(2.3)(36.7)^2=6143 J$

While after the collision

$K_f = \frac{1}{2}mv_A^2+\frac{1}{2}mv_B^2 = \frac{1}{2}(2.3)(25.2)^2+\frac{1}{2}(2.3)(72.4)^2=6758 J$

So, the change in kinetic energy is

$\Delta K = K_f - K_i = 6758-6143 = +615 J$

(note that the system cannot gain kinetic energy in the collision, unless there is an external force acting on it)

3 0

3 years ago