20/40=0.5 g/cm^3 becuase, mass/volume=density.
50(6)=300.
The ball traveled 300 meters in 50 seconds.
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Answer:
Small sparks can lead to huge explosion if they are left unattended.
Explanation:
Small sparks are not harmful but if these sparks happen near some hazardous material or object then it could lead to heavy explosion. If there is some chemical substance near the spark or there are magnetic lines which can explode the spark then these minor sparks could result in heavy disastrous explosion.
Answer:
a). Determine the magnitude of the gravitational force exerted on each by the earth.
Rock: 
Pebble: 
(b)Calculate the magnitude of the acceleration of each object when released.
Rock: 
Pebble: 
Explanation:
The universal law of gravitation is defined as:
(1)
Where G is the gravitational constant, m1 and m2 are the masses of the two objects and r is the distance between them.
<em>Case for the rock </em>
<em>:</em>
m1 will be equal to the mass of the Earth
and since the rock and the pebble are held near the surface of the Earth, then, r will be equal to the radius of the Earth
.

Newton's second law can be used to know the acceleration.

(2)

<em>Case for the pebble </em>
<em>:</em>


Answer: seen below.
Explanation:
Firstly we need to remember what exothermic reaction is in thermodynamics. exothermic reaction describes a process or reaction that releases energy from the system to its surroundings, usually in the form of heat, but also in a form of light, sound, or electricity.
In this scenario, due to the heating up nature noticed by the ring during breaking shows that energy is being released to the surrounding in the form of heat which suggest it being an exothermic reaction.