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Karo-lina-s [1.5K]
3 years ago
9

A car is traveling at 70 km/h. It then uniformly decelerates to a complete stop in 12 s. Find its acceleration ( in m/s2 ).

Physics
2 answers:
Lera25 [3.4K]3 years ago
8 0

Answer:

- 1.62 m/s²

Explanation:

initial velocity, u = 70 km/h = 19.44 m/s

time, t = 12 s

final velocity, v  = 0

Acceleration is defined by the rate of change of velocity.

By use of first equation of motion

v = u + a t

where, a be the acceleration

0 = 19.44 + a x 12

a = - 1.62 m/s²

Thus, the acceleration is - 1.62 m/s².

Yakvenalex [24]3 years ago
5 0

Answer:

Acceleration will be -1.620m/sec^2

Explanation:

We have given initial speed of the car is 70 km/hr

We know that 1 km = 1000 m

And 1 hour = 3600 sec

So 70km/hr=70\times \frac{1000m}{3600sec}=19.444m/sec

It is given that car stops in 12 sec

So final speed of the car v = 0 m/sec

Time t = 12 sec

From first equation of motion v = u+at

So 0=19.444+a\times 12

a=\frac{-19.444}{12}=-1.620m/sec^2 ( negative sign indicates that speed of the car will constantly decrease )

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                                  PE = (mass) x (gravity) x (height) .

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You said that the car's speed is 70 m/s at the bottom of the hill,
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Divide each side by (0.9):

               (0.5/0.9) (4900 m²/s²) = (9.8 m/s²) (height)

Divide each side by (9.8 m/s²):

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                          =        277-7/9    meters
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