Q1. a) av.speed= (v+u)/2
=15m/s
b) a=(v-u)/t
a=(20-10)/60
a=(1/6)m/s2
distance=ut+1/2at2
=(10*60)+1/2*(1/6)*(60)2
=600+300
=900m
Q2. t=(v-u)/a
t=(1100-600)/10
t=500/10
t=50h
Q3. t=(v-u)/a
t=(0-20)/-5
t=-20/-5
t=4s.
Answer to Q2 is wrong in terms of units. It should be 50 seconds, not 50 hours. Because the acceleration is 10km/h per second, not 10km/h per hour.