1. If the car goes from 0 to 80 km in 6 seconds, what acceleration?
2. A jet needs to attain a speed of 200 mph to take off. If it can accelerate from 0 to 200mph in 30s.
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The answers are NOT important, but how to obtain the right ones.
The right answer for number 1 is 19.55 feet/s^2
2006-12-16 17:07:33 · 4 answers · asked by Anonymous in Science & Mathematics ➔ Mathematics
first change the units
goes 0 to 80 km in 60 sec ...it should be 0 to 80 km / hr
so increase in speed is 80-0=80 km/hr or 80,000/60*60 m/sec
22.22 m/sec in 6 sec
=22.22/6=3.70 m/sec^2 (this is correct answer if there is anything else in book then that is wrong)
2006-12-16 17:17:27 · answer #1 · answered by a_m_del_in 2 · 0⤊ 1⤋
Ok, I get it.
1. We're given the final distance, not the speed.
Assume car starts at v=0 at d=0 and begins accelerating at a constant rate.
v=at
d = at^2/2 = 80 km
a = 2(80)/6^2 = 160/36 km/s^2
need to convert units to compare with your answer:
2.54cm/in*12in/ft*1km/10^5cm= 3.048E-4 km/ft
so, 160/36*1/3.048E-4 = .... ft/s^2
I think that you've left out some detail. Physically you don't suddenly start accelerating. The slope of the acceleration must be zero at t=0.
2006-12-16 17:17:50 · answer #2 · answered by modulo_function 7 · 0⤊ 1⤋
ans 1 : a = (v-u)/t
v=80 kmph, u= 0,becoz the car was initialy at rest (u hav given speeded from 0 - 80)
acceleration = 80/6 = 13.33 m/s squared
ie,metre per second^ -2
ans 2 : i didnt get ur question's meaning, u didnt finish it properly
2006-12-16 17:45:12 · answer #3 · answered by Anonymous · 0⤊ 0⤋
80 miles per hour=80*1.47 ft/sec
=117.6 ft /sec
time taken=6 sec
so acceleration=117.6/6=19.55 ft/sec^2
since you have corrected your problem the answer is also correct now!!!
2006-12-17 03:01:44 · answer #4 · answered by raj 7 · 0⤊ 0⤋