Two rather unequal cars are competing in a drag race. For
simplicity, let's assume that the accelerations of the cars are
constant. Car 1 has an acceleration of 3.7 m/s2, while
Car 2 has an acceleration of 6.3 m/s2. Car 2 gets off to
a late start, 1.1 seconds after Car 1.
At what time after Car 1 took off will it be overtaken by Car 2?
(in s)
A: 3.0 | B: 3.8 | C: 4.7 | D: 5.9 | E: 7.4 |
How far down the track will this happen? (in m)
A: 22 | B: 26 | C: 30. | D: 35 | E: 41 |
How much faster will Car 2 be than Car 1 by that time? (in m/s)
A: 3.7 | B: 4.2 | C: 4.7 | D: 5.3 | E: 6.0 |
given that
a1 = 3.7 m/s^2
a2 = 6.3 m/s^2
time difference between both the cars = 1.1 s
(a)
distance covered by car 1 in time t = distance covered by car 2 in time (t-1.1)
1/2*3.7*t^2 = 1/2*6.3*(t-1.1)^2
3,7*t^2 = 6.3 * (t^2 + 1.21 -2.2*t)
2.6*t^2 -13.86*t + 7.623= 0
t = 4.70 s or 0.622 s
answer is C : 4.7 s
(b)
d = 1/2*3.7*4.7*4.7 = 40.86 m
answer is E:41 m
(c)
v1 = a1* t = 3.7*4.7 = 17.39 m/s
v2 = a2*(t-1.1) = 6.3*3.6 = 22.68 m/s
v2 - v1 = 22.68 - 17.39 = 5.29 m/s faster than car 2
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