Reactivity is a chemical property of substance
Answer:
(a) 300 ft
(b) 60 ft/s
Explanation:
distance 
where a is acceleration and t is time
Also, d=vt where v is the velocity
d=30t
Therefore
hence t=10 s
Substituting t is either formula
d=30t=30*10=300 ft
Also
v=at hence 
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When light strikes a black surface, it is reflected by the surface and
nothing is absorbed This would be False because black absorbs the light not reflect
Mirrors are used in telescopes because they have the ability to reflect
True? Telescopes designed with mirrors avoid the problems of refracting telescopes. Because the light is reflected from the front surface only, flaws and bubbles within the glass do not affect the path of the light
Transmission in the passing of light through some materials
False? Some materials allow much of the light that falls on them to be transmitted through the material without being reflected. Materials that allow the transmission of light waves through them are called optically transparent. ... Materials which do not allow the transmission of any light wave frequencies are called opaque.
The mass of the object is the answer of your question
Initial velocity u = 20 m/s
Initial horizontal velocity = 20 cos30° = 20 * 0.866 = 17.32 m/sec.
Initial vertical velocity = 20 sin30° = 20 * 1/2 = 10 m/sec.
time taken t = u/g = 10/10 =1 sec. ( approximating g to 10m/sec^2)
Maximum height h = ut + 1/2 * g * t^2
h = 10 *1 - 1/2 * 10 * 1* 1
h = 10 - 5 = 5 metres.
Total time in air = 2t = 2 seconds.
