Prehistory can be described as _____.

1 answer:

6 0

The in-between period of time when the first man appeared and when man developed a writing system. Or the period of time before man became literate.

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Three guns are aimed at the center of a circle, and each fires a bullet simultaneously. The directions in which they fire are 12

ikadub [295]

Answer:

The unknown mass of the bullet is $m1=3.751x10^{-3} kg$

Explanation:

According to Newton's laws of motion, when a net external force acts on a body of mass <u><em>m</em></u> , it results in change in momentum of the body and is given by:

$F=\frac{P}{dt}$

Where:

is the linear momentum of the body

As a consequence, when there are no external forces acting on the body the total momentum remains conserved i.e.

Given:

$m_{2}=5.79x10^{-3}kg \\m_{3}=5.79x10^{-3}kg\\v_{2}=v_{3}=392 \frac{m}{s}\\$

For momentum along the y-direction to be zero, it is achieved when the equal masses are moving at angles of

θ1=180°, θ2=60°, θ3=-60°

Therefore, from conservation of momentum along x - direction:

$m_{1}*v_{1}*cos(180)+m_{2}*v_{2}*cos(60)+m_{3}*v_{3}*cos(-60)=0\\$ $m_{1}*605\frac{m}{s}*cos(180)+5.79x10^{-3}kg *392\frac{m}{s}*cos(60)+5.79x10^{-3}kg*392\frac{m}{s}*cos(-60)=0\\$

$-m_{1}*605+5.79x10^{-3}kg*196\frac{m}{s}+5.79x10^{-3}kg*196\frac{m}{s}=0\\m_{1}*605kg= 2.26968\frac{kg*m}{s}\\m_{1}=3.75 x10^{-3} kg$

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3 years ago

Which is a future NASA research project? Check all that apply.

Nat2105 [25]

All of the given options represent NASA future projects:

Use a probe to collect data- Parker Solar Probe will be the first-ever mission to study the Sun from such a small distance. The spacecraft will travel directly into the Sun's atmosphere about 4 million miles from the surface.

Improve aviation technology- NASA is currently working on the development of the new experimental aircraft X-plane which will prove the dramatic benefits of advanced technologies in piloted flight.

Conduct research from a space station- Humans are already living and working on board of the International Space Station which is one-of-a-kind research laboratory in microgravity. A portion of the astronauts time aboard the space station has been designated for national laboratory investigations.

Collect samples on an asteroid- First asteroid sample return mission, OSIRIS-REx, arrives at the near-Earth asteroid Bennu in December 2018 and should return a sample for study in 2023.

Conduct an unmanned space mission- InSight Mars lander is set to study the planet’s interior. The Mars 2020 rover will search for signs of past microbial life, gather samples for future return to Earth and investigate resources. The James Webb Space Telescope will be the premier observatory of the next decade, studying every phase in the history of our Universe in infrared

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3 years ago

Until a train is a safe distance from the station, it must travel at 5 m/s. Once the train is on open track, it can speed up to

SIZIF [17.4K]

Answer:

$5 m/s^2$