In the EXPLORE section of your lesson 4.08 on Potential energy there were several animations to watch that provided a graphic illustrating how the PE and KE in a system changed as a skateboarder rides a halfpipe or a pendulum moves, why did the bar for the total energy remain constant? Question 8 options:

all answers given are correct

Energy is converted from kinetic to potential and potential to kinetic, but the total amount of energy is conserved

This is because no energy is being created or destroyed in this system

Because these models do not take into account the impact of friction and air resistance and are helping to solidify the concept of energy conservation and that the total mechanical energy remains constant in that model

1. the materials manager for a billiard ball maker must periodically place orders for resin, one of the raw materials used in producing billiard balls. she knows that manufacturing uses resin at a rate of 50 kilograms each day, and that it costs $.04 per day to carry a kilogram of resin in inventory. she also knows that the order costs for resin are $100 per order, and that the lead time for delivery is four (4) days.2. at what point should resin be reordered? a. 0 kilograms remainingb. 50 kilograms remainingc. 200 kilograms remainingd. 400 kilograms remaininge. 500 kilograms remaining3. if order size was 1,000 kilograms of resin, what would be the length of an order cycle? a. 0.05 daysb. 4 daysc. 16 daysd. 20 dayse. 50 days4. if the order size was 1,000 kilograms of resin, what would be the average inventory level? a. 50 kilogramsb. 200 kilogramsc. 500 kilogramsd. 800 kilogramse. 1,000 kilograms5. if the order size was 1,000 kilograms of resin, what would be the daily total inventory costs, excluding the cost of the resin? a. $5b. $10c. $20d. $25e. $40