Answer:
Explanation:
There are several differences between a physical and chemical change in matter or substances. A physical change in a substance doesn't change what the substance is. In a chemical change where there is a chemical reaction, a new substance is formed and energy is either given off or absorbed.
Answer:
A. 231.77 J
B. 5330.71 J
C. 46 donuts
Explanation:
A. To lift the barbell once, she will have to extend it the full length of her arm. The work done will then be:
W = F * d
Where the force is the weight of the barbell.
F = m * g
Hence, the work done in lifting the barbell is:
W = m * g * d
W = 43 * 9.8 * 0.55
W = 231.77 J
B. If she does 23 repetitions, the total energy she expend will be equal to the Potential energy when the barbell is lifted multiplied by 23:
E = 23 * m * g * d
E = 23 * 231.77
E = 5330.71 J
C. 1 Joule = 4.184 calories
5330.71 Joules = 5330.71 * 4.184 = 22303.69
If 1 donut contains 490 calories, the number of donuts she will need will be:
N = 22303.69/490 = 45.5 donuts or 46 donuts
Let 
be the average acceleration over the first 2.46 seconds, and 
the average acceleration over the next 6.79 seconds.
At the start, the car has velocity 30.0 m/s, and at the end of the total 9.25 second interval it has velocity 15.2 m/s. Let 
be the velocity of the car after the first 2.46 seconds.
By definition of average acceleration, we have
and we're also told that
(or possibly the other way around; I'll consider that case later). We can solve for in the ratio equation and substitute it into the first average acceleration equation, and in turn we end up with an equation independent of the accelerations:
Now we can solve for . We find that
In the case that the ratio of accelerations is actually
we would instead have
in which case we would get a velocity of
Answer:
positive reinforcer; negative reinforcer
Explanation:
positive reinforcer; negative reinforcer
Receiving delicious food can be seen as a positive reinforcer while escaping electric shock can be seen as a negative reinforcer.
