1. Answer: Option C
Displacement is a vector quantity. It has both magnitude as well as direction. Hence, it can be positive, zero or negative. In the given question, downward direction is taken as negative. This we have come to know from the downward acceleration 
. The negative sign indicates that downward direction is considered negative.
Now, since the object is dropped from the top. The displacement should be negative, because the negative represent a downward direction.
2. Answer: velocity
The truck is travelling at 30 mph to the west. From the unit mph (miles per hour), we know its a magnitude of velocity. West indicates the direction. Hence, the given quantity is a vector -velocity.
It is not speed because speed only indicates the magnitude and not the direction. speed is a scalar quantity.
Answer:
Reflection of sound waves also leads to echoes. Echoes are different than reverberations. Echoes occur when a reflected sound wave reaches the ear more than 0.1 seconds after the original sound wave was heard. ... Reflection of sound waves off of curved surfaces leads to a more interesting phenomenon.
Answer:
a. Disk, 28 thousand light-years from
Explanation:
Since, a galactic disc is a component of disc galaxies, for instance spiral galaxies and lenticular galaxies. It consists of a stellar component and a gaseous component.
Also, the Sun lies within the galactic disk or in other words it is thought to be located in the galactic disk,
The Sun is located about 26,000 light-years away from the centre of the galaxy.
∵ From the given options 28,000 is nearest to 26,000
Hence, the sun is about 28 thousand light-years from the centre of the galaxy.
i.e. OPTION 'a' would be correct.
Answer:
21
Explanation: its actually 20.85 but i guess they round to 21
