The amount of heat needed to melt the block of lead is 
Explanation:
The amount of heat needed to melt a solid substance already at its melting point is given by the equation
where
m is the mass of the substance
is the specific latent heat of fusion
In this problem, we have a block of lead already at its melting point, 
. Its mass is
m = 200 g = 0.2 kg
and its specific latent heat of fusion is
Therefore, the amount of heat needed for the block to completely melt is
Learn more about specific heat:
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More force to accelerate. If you push a car compared to a beach ball, which will you have to push harder for it to move? That's pretty much what the question is asking, if that helps any:)
Answer:
The percentage of its mechanical energy does the ball lose with each bounce is 23 %
Explanation:
Given data,
The tennis ball is released from the height, h = 4 m
After the third bounce it reaches height, h' = 183 cm
= 1.83 m
The total mechanical energy of the ball is equal to its maximum P.E
E = mgh
= 4 mg
At height h', the P.E becomes
E' = mgh'
= 1.83 mg
The percentage of change in energy the ball retains to its original energy,
ΔE % = 45 %
The ball retains only the 45% of its original energy after 3 bounces.
Therefore, the energy retains in each bounce is
∛ (0.45) = 0.77
The ball retains only the 77% of its original energy.
The energy lost to the floor is,
E = 100 - 77
= 23 %
Hence, the percentage of its mechanical energy does the ball lose with each bounce is 23 %
The spring potential energy is 1.6 J
Explanation:
The elastic potential energy of a spring is given by the equation:
where
U is the potential energy
k is the spring constant
x is the compression/stretching of the spring
For the spring in this problem, we have:
x = 40 cm = 0.40 m is the stretching
k = 20 N/m is the spring constant
Substituting into the equation, we can find the spring potential energy:
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The river provides fertile soil for farming
