Answer:
yes, 800 has 1 significant digit
neither leading zero nor trelling zero are significant figure except when there's a decimal point
Answer:
80%
Explanation:
Efficiency of machine = work output/work input ×100 %
From question, work output = 20J
Work input = 25J.
Therefore efficiency = 20/25 × 100 %
Efficiency = 20×4 %
Efficiency = 80%
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Answer:
3683.67 m
Explanation:
Formula for maximum height of projectile is given by the equation;
h = u²/2g
Where u is initial velocity and g is acceleration due to gravity
We are given u = 190 m/s
Thus;
h = 190²/9.8
h = 36100/9.8
h = 3683.67 m
Answer a is one of keplers 3 laws
Answer:
a) V = 0.82m/s
b) Vmax = 0.985 m/s
Explanation:
By conservation of energy we know that:
Eo = Ef 
Solving for V we get:
V = 0.82 m/s
To find the maximum speed we will do the same to an intermediate point where the compression is X and the distance for the work donde by frictions is given by (Xmax - X) = (0.28m - X):

Then we have to solve for V, derive and equal zero in order to find position X. After solving the derivative we get:
X = 0.1m Replacing this value into the equation for Vmax:
Vmax = 0.985m/s