Answer:
a)5.88J
b)-5.88J
c)0.78m
d)0.24m
Explanation:
a) W by the block on spring is given by
W= 
kx² = (530)(0.149)² = 5.88 J
b) Workdone by the spring = - Workdone by the block = -5.88J
c) Taking x = 0 at the contact point we have U top = U bottom
So, mg
= kx² - mgx
And, = ( kx² - mgx
)/(mg) = 
]/(0.645x9.8)
= 0.78m
d) Now, if the initial initial height of block is 3
= 3 x 0.78 = 2.34m
then, kx² - mgx - mg =0
(530)x² - [(0.645)(9.8)x] - [(0.645)(9.8)(2.34) = 0
265x² - 6.321x - 14.8 = 0
a=265
b=-6.321
c=-14.8
By using quadratic eq. formula, we'll have the roots
x= 0.24 or x=-0.225
Considering only positive root:
x= 0.24m (maximum compression of the spring)
Answer: To focus on a near object – the lens becomes thicker, this allows the light rays to refract (bend) more strongly. To focus on a distant object – the lens is pulled thin, this allows the light rays to refract slightly.
Explanation:
The volume of a cube is given by:
where L is the measure of each side (which corresponds to its width, since all sides of a cube are equal).
Plugging the data of the problem, L=32.1 cm, inside the equation, we find the volume:
Answer:
a) 245 N
b) 392 J
c) 196 W
Explanation:
a) Force needed to lift the 25 kg object is the same as the weight of the object:
b) Work is the force exerted times the distance moved:
c) The power exerted is the quotient of the work done over the amount of time it took to move the object:
From the point of view of the northern hemisphere:
The sun starts out the year at the Spring equinox, March 21,
Right Ascension 0, Declination 0.
3 months later, Summer solstice, June 21
RA = 6 hours, Dec. = +23.5°
3 months later, Fall equinox, September 21,
RA = 12 hours, Dec. = 0
3 months later, Winter solstice, December 21,
RA = 18 hours, Dec. = -23.5°
