Answer:
0.0059
Explanation:
According to the question the seismic activity density is given by

Here,
Number of Earthquakes over a given time span = 424
The land area affected = 71300 mi²
So,

The seismic activity density is 0.0059
Answer:
I can explain it using the law of force
or Newton's law of motion
Answer:
57 kg
Explanation:
Mass of seesaw = 20 kg
Length of seesaw = 4 m
Mass of child on the longer end = 30 kg
The weight of the seesaw acts at the center i.e. 2m
The algebraic sum of moments of all forces about any point is zero, hence, using the fulcrum as the reference point:
[x * 9.8* 1.5] - [20 * 9.8* (2.5 - 2)] - [30 * 9.8 * 2.5] = 0
=> 14.7x = (20*9.8*0.5) + 735
14.7x = 98 + 735
14.7x = 833
=> x = 833/14.7
x = 57 kg