Answer:
255 Hz
Explanation:
With 5 beats per second with the 250 Hz fork, we know the unknown fork is either 250 - 5 = 245Hz or 250 + 5 = 255 Hz
With 15 beats per second with the 270 Hz fork, we know the unknown fork is either 270 - 15 = 255Hz or 270 + 15 = 285 Hz (most people would have a hard time discerning 15 beats per second... 5 per second is hard enough)
As 255 is the common frequency, it is the one selected.
When Jane is sliding down a slide, she is demonstrating translational motion.
b). The power depends on the RATE at which work is done.
Power = (Work or Energy) / (time)
So to calculate it, you have to know how much work is done AND how much time that takes.
In part (a), you calculated the amount of work it takes to lift the car from the ground to Point-A. But the question doesn't tell us anywhere how much time that takes. So there's NO WAY to calculate the power needed to do it.
The more power is used, the faster the car is lifted. The less power is used, the slower the car creeps up the first hill. If the people in the car have a lot of time to sit and wait, the car can be dragged from the ground up to Point-A with a very very very small power ... you could do it with a hamster on a treadmill. That would just take a long time, but it could be done if the power is small enough.
Without knowing the time, we can't calculate the power.
...
d). Kinetic energy = (1/2) · (mass) · (speed squared)
On the way up, the car stops when it reaches point-A.
On the way down, the car leaves point-A from "rest".
WHILE it's at point-A, it has <u><em>no speed</em></u>. So it has no (<em>zero</em>) kinetic energy.
The answer would be A.
Combination reaction, otherwise known as synthesis reaction, occurs when two or more substances react and form a single, more complex substance.
A combination reaction looks like this in an equation:
<em> A + B </em><em>→ </em><em>AB</em>
reactants product
So from two reactants they become one product.
Let's take a look at choice A.
2H₂O(l) → 2H₂(g) + O₂(g)
reactant product(s)
Notice that from one substance, it broke down into two substances. So this is not a combination reaction. This is what you call a <em>decomposition reaction. </em>
Answer: B
The forklift is doing positive work on the object because the direction of force and the direction of motion are the same. The force of gravity is doing negative work on the object because it is acting opposite to the direction of motion.
Explanation: The work done in lifting an object up is positive when the direction of the displacement and the force applied are in the same direction.
The work will be negative if force and direction of the motion are opposite to each other.
Also, force of gravity is considered positive when an object is moving toward the gravity. That is coming downward. Otherwise, it's negative when it's moving in the opposite direction.
When a forklift raises an object, the forklift is doing positive work on the object because the direction of force and the direction of motion are the same. The force of gravity is doing negative work on the object because it is acting opposite to the direction of motion.
