2. A boy kicks the football of mass 500 g which is initially at rest. It starts moving with a
2 answers:
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(a) Let's convert the final speed of the car in m/s:
The kinetic energy of the car at t=19 s is
(b) The average power delivered by the engine of the car during the 19 s is equal to the work done by the engine divided by the time interval:
But the work done is equal to the increase in kinetic energy of the car, and since its initial kinetic energy is zero (because the car starts from rest), this translates into
(c) The instantaneous power is given by
where F is the force exerted by the engine, equal to F=ma.
So we need to find the acceleration first:
And the problem says this acceleration is constant during the motion, so now we can calculate the instantaneous power at t=19 s:
The kinetic energy of the car at t=19 s is
(b) The average power delivered by the engine of the car during the 19 s is equal to the work done by the engine divided by the time interval:
But the work done is equal to the increase in kinetic energy of the car, and since its initial kinetic energy is zero (because the car starts from rest), this translates into
(c) The instantaneous power is given by
where F is the force exerted by the engine, equal to F=ma.
So we need to find the acceleration first:
And the problem says this acceleration is constant during the motion, so now we can calculate the instantaneous power at t=19 s:
Answer: d. I or II
Explanation: A traveling wave has speed that depends on characteristics of a medium. Characteristics like linear density (μ), which is defined as mass per length.
Tension or Force () is also related to the speed of a moving wave.
The relationship between tension and linear density and speed is ginve by the formula:
So, for the traveling waves generated on a string fixed at both ends described above, ways to increase wave speed would be:
1) Increase Tension and maintaining mass and length constant;
2) Longer string will decrease linear density, which will increase wave speed, due to their inversely proportional relationship;
Then, ways to increase the wave speed is
I. Using the same string but increasing tension
II. Using a longer string with the same μ and T.
Answer:
<h2>A. 6pF</h2>Explanation:
If unknown capacitance C1, C2, C3 and C4 are connected in series to one another, their equivalent capacitance of the circuit will be expressed as shown
Given the capacitance's 3.0 pF, 2.0 pF, 5.0 pF and X pF connected in series to each other. If the equivalent capacitance of the circuit is 0.83 pF, then to get X, we will apply the formula above;
C₄ ≈ 6pF
Hence the value of the X capacitor is approximately 6pF