The top pair of pliers failed to loosen a stubborn bolt, but the bottom pair successfully removed it. Because the contact between the bolt and the pliers working surface is less.
<h3>What is mechanical advantage ?</h3>
Mechanical advantage is a measure of the ratio of output force to input force in a system, it is used to obtained efficiency of the given mechanical machine.
The efficiency to open the stubborn bolt depends upon the contact between the working surface of the pliers and the bolt.
The contact between the bolt and the top pair of pliers working surface is less. Its mechanical advantage is less.
Hence, the top pair of pliers failed to loosen a stubborn bolt, but the bottom pair successfully removed it.
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Cumulonimbus clouds are associated by severe weather. They are thunderstorm clouds that bring heavy rain, snow, hail, lightning and even tornadoes.
Answer:
1) The greatest height attained by the ball equals 20.387 meters.
2) The time it takes for the ball to reach 15 meters approximately equals 1 second.
Explanation:
The greatest height will be attained when the ball stop's in the air and starts falling back to the earth.
thus using third equation of kinematics we obtain the height attained as
where
'v' is the final speed of the ball
'u' is the initial speed of the ball
'a' is the acceleration that the ball is under which in this case equals 9.81 
's' is the distance it covers
Thus for maximum height applying the values in the equation we get
Using the same equation we can find the speed of the ball when it reaches 15 meters of height as
the time it takes to reduce the velocity to this value can be found by first equation of kinematics as
Answer:
2. mechanical weathering can produce smaller pieces of rock that have more surface area for chemical weathering to work Explanation:
Mechanical weathering involves activities of living organisms or some geological processes. The bigger rocks are usually reduced to smaller rocks and further reduction might be limited or not posibble mechanically. This reduced rocks now increases the surface area available for chemical weathering; which further reduces the sizes of the rocks below the size range of mechanical weathering. one will recall that the rate of chemical reaction increases with exposed surface area.
