Gravity increased the downward speed (or decreases the upward speed) by 9.8 m/s every second.
21.2/9.8 = 2.2 seconds
Answer:

Explanation:
The constant speed means that ball is not experimenting acceleration. This elements is modelled by using the following equation of equilibrium:


Now, the exerted force is:

The volume of a sphere is:



Lastly, the force is calculated:


Answer:
Explanation:
Kinetic energy= K.E = (1/2) × mv²
K.E = 0.5× 0.8kg× 100m²/s² = 40 N
Answer:
The average speed of the bus, v = 1.55 m/s
Explanation:
Given that,
Number of blocks traveled by bus towards east = 6
Number of blocks traveled by bus towards north = 8
Length of each block = 100 m
Distance traveled by bus towards east 6 x 100 = 600 m
Distance traveled by bus towards north 8 x 100 = 800 m
The total distance traveled, d = 600 + 800 = 1400
Time taken by the bus to travel is, t = 15 minutes
The velocity is given by the formula
v = d/t m
Substituting the values in the above equation
v = 1400 m /(15 x 60) s
= 1.55 m/s
Hence, the average speed of the bus, v = 1.55 m/s
C. The Densities are equal.
<h3>
What is density?</h3>
Density is mass per unit volume or mass of a unit volume of a material substance.
If m1, V1 and D1 = mass, volume and density respectively of ball C
m2, V2 and D2 = mass, volume and density respectively of ball D
According to the Question ,

Therefore,

Hence, D1 = D2
Learn more about density here:brainly.com/question/15164682
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