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Harrizon [31]
4 years ago
12

A person throws a ball straight up in the air. The ball rises to a maximum height and then falls back down so that the person ca

tches it. Consider the ball while it is in the air. Which of the following statements are true? Just after the ball leaves the person's hand the direction of the acceleration is up. The acceleration is zero when the ball reaches its maximum height. The acceleration is about 9.8 m/s2 (down) when the ball is falling.
Physics
1 answer:
Lana71 [14]4 years ago
5 0

Answer:

The acceleration is about 9.8 m/s2 (down) when the ball is falling.

Explanation:

The ball at maximum height has velocity zero

t = Time taken

u = Initial velocity

v = Final velocity

s = Displacement

a = Acceleration due to gravity = 9.8 m/s² (positive downward and negative upward)

v=u+at\\\Rightarrow 0=u-9.8\times t\\\Rightarrow u=9.8t

The accleration 9.8 m/s² will always be acting on the body in opposite direction when the body is going up and in the same direction when the body is going down. The acceleration on the body will never be zero

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Two planets A and B, where B has twice the mass of A, orbit the Sun in elliptical orbits. The semi-major axis of the elliptical
lozanna [386]

Answer:

2.83

Explanation:

Kepler's discovered that the square of the orbital period of a planet is proportional to the cube of the semi-major axis of its orbit, that is called Kepler's third law of planet motion and can be expressed as:

T=\frac{2\pi a^{\frac{3}{2}}}{\sqrt{GM}} (1)

with T the orbital period, M the mass of the sun, G the Cavendish constant and a the semi major axis of the elliptical orbit of the planet. By (1) we can see that orbital period is independent of the mass of the planet and depends of the semi major axis, rearranging (1):

\frac{T}{a^{\frac{3}{2}}}=\frac{2\pi}{\sqrt{GM}}

\frac{T^{2}}{a^{3}}=(\frac{2\pi }{\sqrt{GM}})^2 (2)

Because in the right side of the equation (2) we have only constant quantities, that implies the ratio \frac{T^{2}}{a^{3}} is constant for all the planets orbiting the same sun, so we can said that:

\frac{T_{A}^{2}}{a_{A}^{3}}=\frac{T_{B}^{2}}{a_{B}^{3}}

\frac{T_{B}^{2}}{T_{A}^{2}}=\frac{a_{B}^{3}}{a_{A}^{3}}

\frac{T_{B}}{T_{A}}=\sqrt{\frac{a_{B}^{3}}{a_{A}^{3}}}=\sqrt{\frac{(2a_{A})^{3}}{a_{A}^{3}}}

\frac{T_{B}}{T_{A}}=\sqrt{\frac{2^3}{1}}=2.83

6 0
3 years ago
Read 2 more answers
An event occurs in system K' at x' = 2 m, y' = 3.7 m, z' = 3.7 m, and t' = 0. System K' and K have their axes coincident at t =
fiasKO [112]

Answer:

Coordinates of event in system K are (x,y,z,t)=(5.103m , 3.7m , 3.7m , 1.57×10⁻⁸s)

Explanation:

To find the coordinates of event in system K ,we have to use inverse Lorentz transformation

So

x=\frac{x^{|}+vt^{|} }{\sqrt{1-\frac{v^{2} }{c{2} } } } \\x=\frac{2m+0.92c(0) }{\sqrt{1-\frac{(0.92c)^{2} }{c{2} } } }\\x=5.103m\\y=y^{|}\\ y=3.7m\\z=z^{|}\\ z=3.7m

for t

r=\frac{1}{\sqrt{1-v^{2} } } \\r=\frac{1}{\sqrt{1-(0.92)^{2} } } \\r=2.551\\t=r(t^{|}+vx^{|}/c^{2}   )\\t=2.551(0s+(0.92c)(2)/c^{2} )\\t=1.57*10^{-8}s

Coordinates of event in system K are (x,y,z,t)=(5.103m , 3.7m , 3.7m , 1.57×10⁻⁸s)

6 0
3 years ago
Thallium consists of 29.5%TI-203 and 70.5%TI-205. What is the relative atomic mass of thallium?
Kazeer [188]
Since you are referring to the TI-203 and TI-205, you need to know the actual masses of these two isotopes. TI-203 has 202.9723 amu  and TI-205 has 204.9744 amu. Since you are concluding that this Thallium have 29.5% (Ti-203) and 70.5% (Ti-205), you need to multiply the percentage to the actual masses of the isotopes. With that, you should be able to get 204.3833 amu
7 0
3 years ago
A child is perched perilously above a 150m ravine. The child has a mass of 45kg. How much
Finger [1]

Answer:

<em>U = 66,150 J</em>

Explanation:

<u>Gravitational Potential Energy</u>

Gravitational potential energy is the energy stored in an object because of its vertical position or height in a gravitational field.

It can be calculated with the equation:

U=m.g.h

Where m is the mass of the object, h is the height with respect to a fixed reference, and g is the acceleration of gravity or 9.8\ m/s^2.

The child of mass m=45 Kg is perched above a h=150 m ravine. His gravitational potential energy is:

U=45~Kg\cdot 9.8\ m/s^2\cdot 150\ m

U = 66,150 J

6 0
3 years ago
Vector B~ has x, y, and z components of 8.7,
blagie [28]

Answer:

The magnitude of B is 10.95\ units

Explanation:

we know that

The magnitude of Vector B is

B=\sqrt{x^{2}+y^{2}+z^{2}}

where

x,y and z are the components of vector B

we have

x=8.7\ units, y=1.4\ units,z=6,5\ units

substitute

B=\sqrt{8.7^{2}+1.4^{2}+6.5^{2}}

B=\sqrt{119.9}

B=10.95\ units

3 0
3 years ago
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