In volleyball, how is the server determined?

A girl coasts down a hill on a sled, reaching level ground at the bottom with a speed of 7.4 m/s. The coefficient of kinetic fri

Amanda [17]

Answer: 62.22 meters

Explanation:

Two solve this, we need to know first how the Sled interact with the snow. While the Sled runs over the snow, the snow opposes to it movement, this is call friction. Frictions creates is a force that goes against any movement and is caused by the interaction between surfaces.

Friction can be calculated using the following equation:

Friction's Force (Ff) = m*N

Where m is the Frictions coficient and N is call Normal, which is a force created by the contact between any weight and a surface. Because the sled is and the surface are totally horizontal, the Normal is equal to the Sled's Weight.

So for this case, we can calculate the Friction's Force:

Ff = 0.045 * 735 N

Ff = 33,07 N

This force will cause a negative acceleration the Sled causing it to slow down and finally stop. To know this accelaration we can use the following equation:

Force (F) = Mass (m) * Accelaration (a)

Looking for the accelaration:

Acceleration (a) = F / M

As a side note:

Mass (M) = F / a (1)

Where we know that F is equal to our Friction Force (Ff) and the Mass for the girl and the Sled can be obtained using the previous equation (1) like this

Girl and sled Mass (M) = 735 N / (9.81 m/s)

M = 74,92 Kg

This is posible, because the Girl and The Sled are aplying a Force on the ground equal to 735 N. The accelartion for their mass is the gravity

Now, with the mass we can found the Accelaration caused by friction:

Acceleration (a) = Ff / M

Accelaration (a) = 33,07 N / 74,92 Kg

a = 0,44 $m/s^{2}$

To know how far the Sled travel we can use the following equation:

$V_{f} ^{2} = V_{0} ^{2} + 2ax$

Where Vf is the Final Velocity, which is when the sled finally stops (Vf = 0), Vo is the Initial Speed of the Sled equal to 7.4 m/s and a is equal to the negative accelaration that causes the friction.

$(0)^{2} = (7.4 m/s)^{2} + 2(-0,44)x$

Searching for x:

$x = \frac{0 - (7.4 m/s)^{2} }{-0.88}$

$x = 62.22 meters$

The girls will run over the snow 62.22 meter until finally stopping

4 0

3 years ago

Your friend, who is in a field 100 meters away from you, kicks a ball towards you with an initial velocity of 16 m/s. Assuming t

LekaFEV [45]

Answer:

Time, t = 5.355 seconds

Explanation:

Given the following data;

Distance = 100 m

Initial velocity = 16 m/s

Deceleration = 1 m/s²

To find the time, we would use the second equation of motion;

But since the ball is decelerating, it's acceleration would be negative.

S = ut + ½at²

Where;

S represents the displacement or height measured in meters.

u represents the initial velocity measured in meters per seconds.

t represents the time measured in seconds.

a represents acceleration measured in meters per seconds square.

Substituting into the equation, we have;

100 = 16t - 0.5t²

200 = 32t - t²

t² + 32t - 200 = 0

Solving the quadratic equation using the quadratic formula;

The quadratic equation formula is;

$x = \frac {-b \; \pm \sqrt {b^{2} - 4ac}}{2a}$

Substituting into the equation, we have;

$x = \frac {-32 \; \pm \sqrt {32^{2} - 4*1*(-200)}}{2*1}$

$x = \frac {-32\pm \sqrt {1024 - (-800)}}{2}$

$x = \frac {-32 \pm \sqrt {1024 + 800}}{2}$

$x = \frac {-32 \pm \sqrt {1824}}{2}$

$x = \frac {-32 \pm 42.71}{2}$

$x_{1} = \frac {-32 + 42.71}{2}$

$x_{1} = \frac {10.71}{2}$

x1 = 5.355

We do not need the negative value of x, so we proceed.

Therefore, time = 5.355 seconds

3 0

3 years ago

If the same pressure is exerted over a greater area will more of less force result? Group of answer choices :

Zigmanuir [339]

Answer:

More force

Explanation:

Pressure and force are related by the equation:

$p=\frac{F}{A}$

where

p is the pressure

F is the force

A is the area

We can re-arrange the equation as

$F=pA$

In this problem, the pressure is kept the same (p' = p) while the area is increased. As we can see from the previous equation, the force applied is directly proportional to the area: therefore, a greater area means also a greater force.

8 0

3 years ago

I need a story about kepler's laws for a child, something a child would understand. And i'd like it to be okay for someone if I

andreyandreev [35.5K]

Answer:

(1) The orbits are ellipses, with focal points ƒ1 and ƒ2 for the first planet and ƒ1 and ƒ3 for the second planet. The Sun is placed in focal point ƒ1.

(2) The two shaded sectors A1 and A2 have the same surface area and the time for planet 1 to cover segment A1 is equal to the time to cover segment A2.

(3) The total orbit times for planet 1 and planet 2 have a ratio a13/2 : a23/2

8 0

3 years ago

Read 2 more answers

A proton initially at rest is accelerated by a uniform electric field. The proton moves 5.62 cm in 1.15 x 10^-6 s. Find the volt

krok68 [10]

Answer:

49.85 V

Explanation:

u = 0, s = 5.62 cm, t = 1.15 x 10^-6 s

Let the electric field is E and voltage is V.

Use second equation of motion

s = ut + 1/2 a t^2

5.62 x 10^-2 = 0 + 0.5 a x (1.15 x 10^-6)^2

a = 8.5 x 10^10 m/s^2

m x a = q x E

E = m x a / q

E = (1.67 x 10^-27 x 8.5 x 10^10) / (1.6 x 10^-19)

E = 887.19 V/m

V = E x s

V = 887.19 x 5.62 x 10^-2 = 49.85 V

4 0

3 years ago