Describe the indifference curves associated with two goods that are perfect substitutes. the indifference curves for two goods that are perfect substitutes
a. have positive slopes.
b. are horizontal lines.
c. are convex.
d. intersect one another.
e. are downward-sloping straight lines.

You want to move a heavy box with mass 30.0 kg across a carpeted floor. you pull hard on one of the edges of the box at an angle 30∘ above the horizontal with a force of magnitude 240 n, causing the box to move horizontally. the force of friction between the moving box and the floor has magnitude 41.5 n . what is the box's acceleration just after it begins to move