Why does a 10 gram piece if copper take up more space than a 10 gram piece of gold
1 answer:
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Answer:
B) A stack of books is carried at waist level across a room
Explanation:
Work is defined as:
where
F is the force applied
d is the displacement of the object
is the angle between the direction of the force and of the displacement
From the formula, we see that the work done is zero when the force and the displacement are perpendicular to each other. Let's now analyze each situation:
A) A bookcase is slid across carpeting. --> work is done, because the force that pushes the bookcase is in the same direction of the displacement
B) A stack of books is carried at waist level across a room. --> no work is done, because the force to carry the book is vertical, while the displacement of the books is horizontal
C) A chair is lifted vertically with respect to the floor. --> work is done, because the force that lifts the chair is vertical, and the displacement is vertical as well
D) A table is dropped onto the ground. --> work is done, because the force of gravity (that makes the table falling down) is vertical and the displacement of the table is also vertical.
The question is missing a diagram of the ray reflection. I attached a diagram which comes from a similar question in the answer section. The full question should be as follows:
Two plane mirrors intersect at right angles. A laser beam strikes the first of them at a point d = 10.0cmfrom their point of intersection, as shown in the figure. For what angle of incidence at the first mirror will this ray strike the midpoint of the second mirror (which is s=29.0cm long) after reflecting from the first mirror?
Answer:
34.6°
Explanation:
To strike the midpoint of the second mirror, the ray light will have to travel half of the distance vertically
i.e. 29/2 = 14.5
We can solve this through trigonometry.
Let the angle between the ray and the vertical plane mirror is known as α
tan α = 10/14.5
α = = 34.6°
The angle of incidence is the angle between the ray and the normal line of the mirror.
Let angle of incidence of first mirror be β
β = α = 34.6
Answer:
12 ounces of beer plus 12 ounces of wine plus 3 ounces of liquor are equivalent to 6 drinks.
Explanation:
In the United States, a standard "drink" of beer has 12 ounces, a standard "drink" of wine has 5 ounces and standard drink of liquor has 1.5 ounces. Then, we obtain the quantity of drinks by dividing the total volume of each drink by its respective unit volume and summing each term. That is:
12 ounces of beer plus 12 ounces of wine plus 3 ounces of liquor are equivalent to 6 drinks.