A

A ball is projected into the air with 100 j of kinetic energy which is transformed to gravitational potential energy at the top

raketka [301]

<span>when it returns to its original level after encountering air resistance, its kinetic energy is decreased.
In fact, part of the energy has been dissipated due to the air resistance.

The mechanical energy of the ball as it starts the motion is:
</span> $E=K = 100 J$
<span>where K is the kinetic energy, and where there is no potential energy since we use the initial height of the ball as reference level.
If there is no air resistance, this total energy is conserved, therefore when the ball returns to its original height, the kinetic energy will still be 100 J. However, because of the presence of the air resistance, the total mechanical energy is not conserved, and part of the total energy of the ball has been dissipated through the air. Therefore, when the ball returns to its original level, the kinetic energy will be less than 100 J.</span>

3 0

3 years ago

10) A soccer player kicks a soccer ball (m = 0.42 kg) accelerating from rest to 32.5m/s in 0.21s. Determine the force that sends

MaRussiya [10]

Explanation:

(10) Mass of a soccer player, m = 0.42 kg

Initial speed, u = 0

Final speed, v = 32.5 m/s

Time, t = 0.21 s

We need to find the force that sends soccer ball towards the goal.

Force, F = ma

$F=\dfrac{m(v-u)}{t}\\\\F=\dfrac{0.42 \times (32.5-0)}{0.21}\\\\F=65\ N$

So, 65 N of force soccer ball sends towards the goal.

(11) Mass of the satellite, m = 72,000 kg

Initial speed, u = 0 m/s

Final speed, v = 0.63 m/s

Time, t = 1296 s

We need to find the force is exerted by the rocket on the satellite.

Force, F = ma

$F=\dfrac{m(v-u)}{t}\\\\F=\dfrac{72,000\times (0.63-0)}{1296}\\\\F=35\ N$

So, 35 N of the force is exerted by the rocket on the satellite.

Hence, this is the required solution.

3 0

2 years ago

A uniform rod of length 0.8 m and mass 1.4 kg, has two point masses at each end. The point mass on the left end has a mass 1.2 k

VladimirAG [237]

Answer:

Explanation:

1.2(0) + 3(0.8) + 1.4(0.8/2) / (1.2 + 3 + 1.4) = 0.5285714... ≈ 0.53 m

5 0

3 years ago

A friend in your class tells you that she never uses hints when doing her Mastering homework. She says that she finds the hints

AnnZ [28]

Answer:

A, B, and C are good reasons for my friend not to worry

Explanation:

The following reasons are reason not to worry

A. The only way to lose additional partial credit on a hint is by using the "give up" button or entering incorrect answers. Leaving the question blank will not cost you any credit (Regardless of whether you open a link or not, you will lose credit if you enter a wrong answer or if you give up on a question by hitting the "give up" button. Even after opening a hint, you can leave the question blank if the hint does not provide relevant hints or if the hint brings up more question. Once the question is left blank, you do not lose additional partial credit)

B. As an incentive for thinking hard about the problem, your instructor may choose to apply a small hint penalty, but this penalty is the same whether the hint simply gives information or asks another question (In a situation where you decide to use a hint, the instructor may have put a penalty for using the hint, so whether it asks a question or help in the solution of the question, as long as the hint is consulted, the hint penalty still applies)

C. Getting the correct answer to the question in a hint actually gives you some partial credit, even if you still can't answer the original question (An advantage of using hint is that you get some partial credit for using it if you answer the hint question correctly and fails to answer the original question)

6 0

3 years ago

Which of the following is NOT an indicator of a physical change?

S_A_V [24]

Answer:

1. C. The change is easily reversible

2. A. a physical change

Explanation:

Happy Holidays

8 0

3 years ago