Answer:
V= 33.98 m/s
Explanation:
Given that
Horizontal speed ,u= 17 m/s
Time taken by rockets to strike the water ,t= 3 s
We know that acceleration due to gravity ,g= 9.81 m/s²
There is no any acceleration in the horizontal direction that is why the horizontal veloity will remain constant.
In the vertical direction
vy = uy+ g t
Initial velocity in vertical direction is 0 m/s.
vy= 0+ 9.81 x 3
vy = 29.43 m/s
The resultant velocity
V= 33.98 m/s
For the first one, the correct answer would be "<span>Substance changes its form but not its molecular composition.". During a physical change (let's say cutting paper), the substance has its shape changed, but it is still itself (paper).
</span><span>The second one is a bit trickier: </span>
Kinetic energy of a molecule is directly influenced by temperature. If there is a higher temperature it will have a higher kinetic energy which means the molecule moves at a higher velocity. This will increase the chance of particles bouncing off of each other during the chemical reaction. That explains why the rate of reaction will be higher at a higher temperature, rather than higher at a cool temperature. The correct answer would be lower at 39F.
The first question is how much of a voltage increase are we looking at. If it has a 110 voltage rating and you put it across a 220 source, you will see one flash and then the bulb is no more. Nothing will revive it.
If it is rated at 110 and you put 130 across it, there's no problem but the bulb will burn out sooner than it would if you just put 110 across it.
So you raise the voltage and the resistance stays the same, the current will increase. That's why it will burn out sooner.
V = I * R
The equation is a direct variation. If the voltage goes up the current goes up. If the voltage goes down, the current goes down providing that the resistance stays the same in both cases.
The second question is what is resistance? Resistance in Electricity is the ability of an electric current to go in one direction freeing up as many electrons as it can. The MORE free electrons, the lower the resistance. The FEWER free electrons the higher the resistance.
Here' the kicker. Ready? More and Less are probably the two most important words in beginning science.
The <u><em>More</em></u> the resistance, the <em><u>Less</u></em> the current flow. That's a really important consideration in battery drain in a watch (or modern day calculator). The More the Battery Drain, the Less time it will last.
Always be careful when more and Less are around.
In my opinion, the third answer makes the most sense
We have to calculate the period when we know the frequency of a sound wave. Period and frequency are related quantities. They are reciprocal of each other.
T = 1/f, where T is the period ( in seconds ) and f is the frequency ( in Hz ).
T = 1/220 Hz;
Answer: T = 0.0045 s.
