To establish the age of a rock or a fossil, researchers use some type of clock to determine the date it was formed. Geologists commonly use radiometric dating methods, based on the natural radioactive decay of certain elements such as potassium and carbon, as reliable clocks to date ancient events.
The answer is A. They are both processes in which water is changed into water vapor.
Force required to move a block is 1.615 N
Given:
mass of block = m = 150 pounds = 68 kg
distance = d = 5 ft = 1.52 metres
time = t = 8 sec
To Find:
force required to move the block
Solution: Force is defined as product of mass and acceleration and it's unit is N or Newton.
Velocity = displacement/ time = 1.52 / 8 = 0.19 m/s
Acceleration = velocity/time = 0.19/8 =
0.023 m/s^2
Force = mass x acceleration = 68x0.023 = 1.615 N
Hence, force required to move the block is 1.615 N
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<u>Answer:</u>
<em>The initial distance between the trains is 1450 m.
</em>
<u>Explanation:</u>
In the question two trains are of equal length 400 m and moves at a uniform speed of 72 km/h. train A is moving ahead of train B. If the train B has to overtake train A it should accelerate.
Train B’s acceleration is 
and it accelerated for 50 seconds.
<em>
</em>
<em>t=50 s
</em>
<em>initial speed u=72km/h
</em>
<em>we have to convert this speed into m/s </em>
<em>
</em>
<em>Distance covered in accelerating phase 
</em>
<em>
</em>
<em>
</em>
If a train is just behind another, the distance covered by the train located behind during overtaking phase will be equal to the sum of the lengths of the trains.
<em>Here length of train A+length of train 
</em>
<em>Hence the initial distance between the trains = 
</em>
