It is about finding kinetic energy want help in part 1 not part 2 in part 1 please tell how to find velocity?
1 Answer
(i) Driving Force of the engine
At the bottom of hill
Net force upwards
Using Newton's Second Law of motion
This must be
#="Mass of car" xxa_"bottom"=1250xx4#
Therefore we get
#30000/v_"bottom"-1000-735.75=5000#
#=>30000/v_"bottom"=6735.75#
#=>v_"bottom"=4.45\ ms^-1# , rounded to two decimal places
Similarly for
#30000/v_"top"-1000-735.75=1250xx0.2#
#=>v_"top"=15.11\ ms^-1# , rounded to two decimal places
Gain in KE
(ii) Work Done by car’s engine
#"Gain in KE"# from part (i)#"Gain in PE"\ =mgh=1250xx9.81xx30=367875\ J# #"Work Done against resistance"="resistance"xx"distance"#
#=1000xx500=500000\ J#
(I have used
Hope this helps.