C light energy
The solar energy from the sun converts to chemical potential energy
Combustion Engine Exhaust----Cars, trucks, jet airplanes and other combustion engine vehicles cause air pollution. The exhaust from these contains carbon monoxide, nitrous oxide and gaseous oxide. This type of air pollution creates smog
Since momentum is a vector quantity, take any direction as positive and other as negative. Answer won't change.
Finding acceleration= final speed-initial speed/time taken (or A=V-U\T)
Finial speed= 27.8s
Initial speed= 0s
Time taken= 5.15
So..
27.8-0/5.15= 5.40m/s (rounded to two decimal places)
No additional force is required because it's already going downhill