A weightlifter uses a force of 356 N to lift a set of weights 2.2 m off the ground. How much work did the weightlifter do? Answe
1 answer:
Answer:
783.2 N.m or Joules
Explanation:
Work done when a force F is applied to move an object by a displacement d meters
where cos(Ф) is the angle between applied force F and displacement d
Since the weightlifter is applying the force upward and the set of weight also move upward therefore, both are in same direction hence angle will be zero.
Now lets substitute the given values into the work equation:
since cos(0)=1
or
Since the unit of Force is Newton (N) and the unit of displacement is meters (m) therefore, unit of work done will be N.m
Note: 1 N.m is equivalent to 1 joule
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Answer:
15.8 V
Explanation:
The relationship between capacitance and potential difference across a capacitor is:
where
q is the charge stored on the capacitor
C is the capacitance
V is the potential difference
Here we call C and V the initial capacitance and potential difference across the capacitor, so that the initial charge stored is q.
Later, a dielectric material is inserted between the two plates, so the capacitance changes according to
where k is the dielectric constant of the material. As a result, the potential difference will change (V'). Since the charge stored by the capacitor remains constant,
So we can combine the two equations:
and since we have
V = 71.0 V
k = 4.50
We find the new potential difference: