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 for3s can be found from the kinematic expressionv=u+at
:.v_1=0+16xx3=48ms^-1 .
Distance moved in these3s can be calculated by the kinematic expression
s=ut+1/2at^2
:.s_13=0xx3+1/2xx16xx3^2=72m
Crash occurs after9-3=6s when he stops accelerating.
Distance moved during these6s 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 for5s v_2=0+20xx5=100ms^-1 .
Distance moved in these5s
s_25=0xx5+1/2xx20xx5^2=250m
Crash occurs after9-5=4s when he stops accelerating.
Distance moved during these4s
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