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ollegr [7]
3 years ago
15

(This is a non-relativistic warm-up problem, to get you to think about reference frames.) A girl throws a baseball upwards at ti

me t=0. She catches it at exactly t=2.0 seconds. A) Calculate the position of the ball as a function of time (0
Physics
1 answer:
____ [38]3 years ago
5 0

Answer:

X(t) = 9.8 *t - 4.9 * t^2

Explanation:

We set a frame of reference with origin at the hand of the girl the moment she releases the ball. We assume her hand will be in the same position when she catches it again. The positive X axis point upwards.The ball will be subject to a constant gravitational acceleration of -9.81 m/s^2.

We use the equation for position under constant acceleration:

X(t) = X0 + V0 * t + 1/2 * a *t^2

X0 = 0 because it is at the origin of the coordinate system.

We know that at t = 2, the position will be zero.

X(2) = 0 = V0 * 2 + 1/2 * -9.81 * 2^2

0 = 2 * V0 - 4.9 * 4

2 * V0 = 19.6

V0 = 9.8 m/s

Then the position of the ball as a function of time is:

X(t) = 9.8 *t - 4.9 * t^2

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think of two school rules and briefly describe how these rules help protect health and why its important to follow them.
Softa [21]

Answer:

Wash your hand when you are done using the restroom because you could spread germs if not.

Don't come to school if you are sick because then you will get others sick.

Explanation:

5 0
4 years ago
Read 2 more answers
The surface temperature of a planet depends on both the distance of the planet from the Sun and on how the panet's atmosphere di
BaLLatris [955]

Answer:

Aphelion: 6404 W/m2

Perihelion: 14978 W/m2

Explanation:

The solar energy flux depends on the solar power output divided by the surface of a sphere with a radius equal to the distance to the Sun.

\Phi sol = \frac{Psol}{4 * \pi * d^2}

The distances we need are the aphelion and perihelion of Mercury.

Planetary orbits are ellipses. In an ellipse the eccentricity is related to linear eccentricity and the length of the semi major axis:

e = \frac{c}{a}

Where

e: eccentricity

c: linear eccentricity

a: semi major axis

The linear eccentricity is equal to the distance of the focus of the center of the ellipse.

c = a * c =

a = 0.39 AU = 5.83e10 m

c = 5.83e10e * 0.21 = 1.22e10 m

In planetary orbits the Sun is in one of the fucuses. With this we can calculate the prihelion and aphelion as:

Ap = a + c = 5.83e10 + 1.22e10 = 7.05e10 m

Pe = a - c = 5.83e10 - 1.22e10 = 4.61e10 m

And the solar energy fluxes will be:

\Phi Ap = \frac{4e26}{4 * \pi * 7.05e10^2} = 6404 W/m2

\Phi Pe = \frac{4e26}{4 * \pi * 4.61e10^2} = 14978 W/m2

4 0
3 years ago
Question 2 (4 points) The cause of heat cramps is the loss of sodium and potassium through heavy sweating? True False ​
sattari [20]

Answer:

True

Explanation:

Lose of water content in our body through sweating and lose of essential salts such as potassium and sodium causes heat cramps...

Thank you

8 0
4 years ago
what is the magnitude of the compression forces (assumed to be horizontal) acting on both sides of the center board that is sand
Len [333]

F = normal force by each board on each side

W = weight of the board in between acting in down direction = 95.5 N

f = frictional force in upward direction by each board

\mu = coefficient of friction = 0.663

Using equilibrium of force in Upward direction

f + f = W

f = W/2

f = 95.5/2 = 47.75 N

frictional force is given as

f = \mu F

47.75 = (0.663) F

F = 72.02 N

4 0
3 years ago
A skier starts from rest at the top of a hill that is inclined 10.5° with respect to the horizontal. The hillside is 200 m long,
Svetlanka [38]

Answer:

d) 289.31 m

Explanation:

Energy provided by potential energy = mgh = m x 9.8x 200 sin10.5 = 357.18m

Energy used by friction = μmgcos 10.5 x 200 = .075 x m x 9.8 x cos 10.5 x200 = 144.54 m .

Energy used by friction on plain surface = μmg x d.( dis distance covered on plain ) =.075x m x 9.8 xd = .735 m d

To equate

357.18 m -144.54 m = .735 m d

d = 289.31 m .

4 0
3 years ago
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