How to find the length of the track?
Can someone please explain to me how to do question 5? Thanks!
Can someone please explain to me how to do question 5? Thanks!
1 Answer
Dec 26, 2017
- First driver. He starts with initial velocity
#=0# .
His velocity after accelerating for#3s# can be found from the kinematic expression#v=u+at#
#:.v_1=0+16xx3=48ms^-1# .
Distance moved in these#3s# can be calculated by the kinematic expression
#s=ut+1/2at^2#
#:.s_13=0xx3+1/2xx16xx3^2=72m#
Crash occurs after#9-3=6s# when he stops accelerating.
Distance moved during these#6s# can be found from the expression
#s=vt#
#s_16=48xx6=288m#
Total distance moved by first driver#=72+288=360m# - Second driver. He too starts with initial velocity
#=0# .
His velocity after accelerating for#5s# #v_2=0+20xx5=100ms^-1# .
Distance moved in these#5s#
#s_25=0xx5+1/2xx20xx5^2=250m#
Crash occurs after#9-5=4s# when he stops accelerating.
Distance moved during these#4s#
#s_24=100xx4=400m#
Total distance moved by second driver#=250+400=650m#
Length of track#=# Sum of distances moved by both drivers
#=288+650=938m#
