1) The kinetic energy of an object is given by:
where m is the object's mass and v its speed.
By using this equation, we find the initial kinetic energy of the skateboarder:
and the final kinetic energy as well:
So, her change in kinetic energy is
2) The work-energy theorem states that the work done to increase the speed of an object is equal to the variation of kinetic energy of the object:
Therefore, the work done by the skateboarder is
Answer:
Two resistors in parallel can be placed in series with the third.
Two resistors in series can be placed in parallel with the third.
The resistors can all be connected in series.
The resistors can all be connected in parallel.
Explanation:
When we want to connect three resistors in a circuit, four options are open to us; these options are:
Two resistors in parallel can be placed in series with the third.
Two resistors in series can be placed in parallel with the third.
The resistors can all be connected in series.
The resistors can all be connected in parallel.
In each case we obtain an equivalent or net resistance. We cannot connect the resistors to the equivalent resistance since the equivalent resistance is obtained from the arrangement of the three resistors in each case.
For this case we have, by definition, that:
Resistance is a component that is responsible for limiting the amount of current that can pass through a circuit, converting excess heat.
Consume energy.
Option A represents a swicth, option B represents a luminaire and option D represents a voltage source.
So, the correct option is C,
Answer:
Option C
Answer:
Vf = 23 m/s
Explanation:
First we need to find the distance covered by the motorcycle 2 when it passes motorcycle 1. Using the uniform speed equation for motorcycle 1:
s₁ = v₁t₁
where,
s₁ = distance covered by motorcycle 1 = ?
v₁ = speed of motorcycle 1 = 6.5 m/s
t₁ = time = 10 s
Therefore,
s₁ = (6.5 m/s)(10 s)
s₁ = 65 m
Now, for the distance covered by motorcycle 2 at the meeting point. Since, the motorcycle started 50 m ahead of motorcycle 2. Therefore,
s₂ = s₁ + 50 m
s₂ = 65 m + 50 m
s₂ = 115 m
Now, using second equation of motion for motorcycle 2:
s₂ = Vi t + (1/2)at²
where,
Vi = initial velocity of motorcycle 2 = 0 m/s
Therefore,
115 m = (0 m/s)(10 s) + (1/2)(a)(10 s)²
a = 230 m/100 s²
a = 2.3 m/s²
Now, using 1st equation of motion:
Vf = Vi + at
Vf = 0 m/s + (2.3 m/s²)(10 s)
Vf = 23 m/s