if you drive 30 miles in 40 minutes, and then 15 miles in 20 minutes, do you have a constant speed?

a) yes

b) no

c) maybe, depending on the instantaneous speed at each instant of the trip

d) maybe, depending on the car

A) yes

Explanation:

First section of trip: 30 miles in 40 minutes

Second section of trip: 15 miles in 20 minutes

The formula for speed is distance over time

Calculate the speeds for each section of the trip.

First:

k = d/t

k = 30miles/40minutes  <= reduce fraction by 10 (30÷10 and 40÷10)

k = 3 miles / 4 minutes

Second:

k = d/t

k = 15miles/20minutes  <= reduce fraction by 5 (15÷5 and 20÷5)

k = 3 miles / 4 minutes

Therefore there is a constant speed because both sections of the trip are driving at "3 miles / 4 minutes".

3 miles / 4 minutes can be also formatted as:

0.75 miles per minute.

second mirror gathers light from a faraway object and reflects it to another mirror. - a.

answer: 802.3 kilo joules of energy represents 191.75 kilo calorie of energy.

explanation:

energy released during combustion of one mole methane = 802.3 kilo joules

if 1 kilo joule = 0.239006   kilo calorie

then ,802.3 kilo joule will be = 802.30.239006 kilo calorie

802.3 kilo joule = 191.75 kilo calorie

hence, the energy in kilo calorie is 191.75 kilo calorie.