Answer:
d. 100.0 J
Explanation:
To solve this problem we must use the theorem of work and energy conservation. This tells us that the mechanical energy in the final state is equal to the mechanical energy in the initial state plus the work done on a body. In this way we come to the following equation:
E₁ + W₁₋₂ = E₂
where:
E₁ = mechanical energy at state 1. [J] (units of Joules)
E₂ = mechanical energy at state 2. [J]
W₁₋₂ = work done from 1 to 2 [J]
We have to remember that mechanical energy is defined as the sum of potential energy plus kinetic energy.
The energy in the initial state is zero, since there is no movement of the hockey puck before imparting force. E₁ = 0.
The Work on the hockey puck is equal to:
W₁₋₂ = 100 [J]
100 = E₂
Since the ice rink is horizontal there is no potential energy, there is only kinetic energy
Ek = 100 [J]
It can be said that the work applied on the hockey puck turns into kinetic energy
Answer:
Explanation:
Given that:
A circuit with a lagging 0.7 pf delivers 1500 watts and 2100VA
Here:
the initial power factor i.e cos θ₁ = 0.7 lag
θ₁ = cos⁻¹ (0.7)
θ₁ = 45.573°
Active power P = 1500 watts
Apparent power S = 2100 VA
What amount of vars must be added to bring the pf to 0.85
i.e the required power factor here is cos θ₂ = 0.85 lag
θ₂ = cos⁻¹ (0.85)
θ₂ = 31.788°
However; the initial reactive power 
= P×tanθ₁
the initial reactive power = 1500 × tan(45.573)
the initial reactive power = 1500 × 1.0202
the initial reactive power = 1530.3 vars
The amount of vars that must therefore be added to bring the pf to 0.85
can be calculated as:
(a) By definition of average acceleration,
<em>a</em> = ∆<em>v</em> / ∆<em>t</em> = (0 - 38 m/s) / (5.0 s)
<em>a</em> = -7.6 m/s²
(b) Recall that
<em>v</em>² - <em>u</em>² = 2 <em>a</em> ∆<em>x</em>
where <em>u</em> and <em>v</em> are initial and final velocities, respectively; <em>a</em> is acceleration; and ∆<em>x</em> is the change in position. So
0² - (38 m/s)² = 2 (-7.6 m/s²) ∆<em>x</em>
∆<em>x</em> = 95 m
Capillary action<span> occurs when the adhesion to the walls is stronger than the cohesive</span>forces<span> between the liquid molecules. The </span>height to which capillary action will take water<span> in a uniform circular </span>tube<span> (picture to left) is limited by surface tension and, of course, gravity.
Hope this helps. :)</span>
