Answer:
a
![l_o =52 \ m](https://tex.z-dn.net/?f=l_o%20%20%3D52%20%5C%20%20m)
b
![l = 37.13 \ LY](https://tex.z-dn.net/?f=l%20%3D%2037.13%20%5C%20LY)
Explanation:
From the question we are told that
The speed of the spaceship is ![v = 0.800c](https://tex.z-dn.net/?f=v%20%20%3D%20%200.800c)
Here c is the speed of light with value ![c = 3.0*10^{8} \ m/s](https://tex.z-dn.net/?f=c%20%3D%20%203.0%2A10%5E%7B8%7D%20%5C%20m%2Fs)
The length is ![l = 31.2 \ m](https://tex.z-dn.net/?f=l%20%3D%2031.2%20%5C%20%20m)
The distance of the star for earth is ![d = 145 \ light \ years](https://tex.z-dn.net/?f=d%20%3D%20145%20%5C%20%20light%20%5C%20%20years)
The speed is ![v_s = 2.90 *10^{8}](https://tex.z-dn.net/?f=v_s%20%3D%202.90%20%2A10%5E%7B8%7D)
Generally the from the length contraction equation we have that
![l = l_o \sqrt{1 -[\frac{v}{c } ]}](https://tex.z-dn.net/?f=l%20%20%3D%20%20l_o%20%20%5Csqrt%7B1%20-%5B%5Cfrac%7Bv%7D%7Bc%20%7D%20%5D%7D)
Now the when at rest the length is ![l_o](https://tex.z-dn.net/?f=l_o)
So
![l_o =\frac{l}{\sqrt{ 1 - \frac{v^2}{c^2 } } }](https://tex.z-dn.net/?f=l_o%20%3D%5Cfrac%7Bl%7D%7B%5Csqrt%7B%201%20-%20%5Cfrac%7Bv%5E2%7D%7Bc%5E2%20%7D%20%7D%20%7D)
![l_o =\frac{ 31.2 }{ \sqrt{1 - \frac{(0.800c ) ^2}{c^2} } }](https://tex.z-dn.net/?f=l_o%20%3D%5Cfrac%7B%2031.2%20%7D%7B%20%5Csqrt%7B1%20-%20%5Cfrac%7B%280.800c%20%29%20%5E2%7D%7Bc%5E2%7D%20%7D%20%7D)
![l_o=52 \ m](https://tex.z-dn.net/?f=l_o%3D52%20%5C%20%20m)
Considering b
Applying above equation
![l =l_o \sqrt{1 - [\frac{v}{c } ]}](https://tex.z-dn.net/?f=l%20%20%3Dl_o%20%5Csqrt%7B1%20-%20%20%5B%5Cfrac%7Bv%7D%7Bc%20%7D%20%5D%7D)
Here ![l_o =145 \ LY(light \ years )](https://tex.z-dn.net/?f=l_o%20%20%3D145%20%5C%20%20LY%28light%20%5C%20years%20%29)
So
![l=145 * \sqrt{1 - \frac{v_s^2}{c^2 } }](https://tex.z-dn.net/?f=l%3D145%20%2A%20%20%5Csqrt%7B1%20-%20%20%5Cfrac%7Bv_s%5E2%7D%7Bc%5E2%20%7D%20%7D)
![l =145 * \sqrt{ 1 - \frac{2.9 *10^{8}}{3.0*10^{8}} }](https://tex.z-dn.net/?f=l%20%3D145%20%2A%20%20%5Csqrt%7B%201%20-%20%5Cfrac%7B2.9%20%2A10%5E%7B8%7D%7D%7B3.0%2A10%5E%7B8%7D%7D%20%7D)
![l = 37.13 \ LY](https://tex.z-dn.net/?f=l%20%3D%2037.13%20%5C%20LY)
A mercury filled balloon would fall faster then water. Mercury is heavier.
Answer:
The body is said to be in static equilibrium if the net force acting on a body at rest is zero.As the net force is zero,the body will not undergo motion.
Explanation:
Explanation:
The net force would be upwards since the kangaroo would have to overcome gravity to jump
Answer:
D. 130 J
Explanation:
The coefficient of performance for a machine that is being used to cool, is given by:
![COP=\frac{Q_C}{W}=\frac{T_C}{T_H-T_C}](https://tex.z-dn.net/?f=COP%3D%5Cfrac%7BQ_C%7D%7BW%7D%3D%5Cfrac%7BT_C%7D%7BT_H-T_C%7D)
Here
is the heat removed from the cold reservoir, W is the work required, that is, the energy required to remove the heat from the interior of the house,
is the cold temperature and
is the hot temperature. Recall use absolutes temperatures(
). Replacing and solving for W:
![W=Q_c\frac{T_H-T_C}{T_C}\\W=2000J\frac{312.15K-293.15K}{293.15K}\\W=129.63J](https://tex.z-dn.net/?f=W%3DQ_c%5Cfrac%7BT_H-T_C%7D%7BT_C%7D%5C%5CW%3D2000J%5Cfrac%7B312.15K-293.15K%7D%7B293.15K%7D%5C%5CW%3D129.63J)