To measure the strength of an earthquake, you can use either a Richter scale or Mercalli scale. Richter scale uses the amplitued of the wave and the distance from the source. Mercalli scale uses observations of people and is not considered to be scientific as Richter scale.
This question involves the concepts of average speed, distance, and time.
The average speed of the family is "2.5 mi/hr".
<h3>AVERAGE SPEED</h3>
The average speed is defined as the ratio of the total distance covered with the total time taken to cover it.

where,
- s = distance covered = 2.5 miles
- t = total time taken = 1 hour
- v = average speed = ?
Therefore,

v = 2.5 mi/hr
Learn more about average speed here:
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Answer:
buoyant force on the block due to the water= 10 N
Explanation:
We know that
buoyant force(F_B) on a block= weight of the block in air (actual weight) - weight of block in water.
Given:
A block of metal weighs 40 N in air and 30 N in water.
F_B = 40-30= 10 N
therefore, buoyant force on the block due to the water= 10 N
Answer:
0.1040512455 N

0.05925 N

Explanation:
I = Current
B = Magnetic field
Separation between end points is

Effective force is given by

The force is 0.1040512455 N

The angle the force makes is given by

The direction is 

The force is 0.05925 N


The direction is 
Answer:
<em>An average net force of 5200 N is needed to stop the car</em>
Explanation:
<u>Cinematics and Dynamics</u>
Cinematics describes the variables involved in the movement without dealing with its causes. There are four main concepts in cinematics: Velocity (or its scalar equivalent, the speed), acceleration, time, and displacement (or the scalar equivalent, distance).
The acceleration can be calculated by:

The initial speed is vo=28 m/s, it stops (vf=0) in t=10.5 seconds, thus the acceleration is:


The acceleration is negative because the car loses speed.
Knowing the mass of the car m=1950 Kg, we can calculate the net force required to stop the car by using the formula:
F = m.a =1950*2.67
F = 5200 N
An average net force of 5200 N is needed to stop the car