Acar starting from rest accelerates at a constant 2.0 m/s2 for 10 s. it then travels with constant speed it has achieved for another 10 s. then it finally slows to a stop with constant acceleration of magnitude 2.0 m/s2. how far does it travel after starting?

The total distance will be 400 m.

Explanation:

For portion AB:

Acceleration = 2

t= 10 s

Car start from rest , u=0 m/s

We know that

S= 100 m.

For portion BC:

V= u + at

V=0 + 2 x 10

V= 20 m/s

In this portion car moves with constant velocity  20 m/s for 10 s.

So distance S= V x t

S=20 x 10 =200 m.

For portion CD:

The velocity at point C will be 20 m/s

In this portion the final speed of car will be zero because given that at final car come to rest.

So the acceleration will be in the negative direction to stop the car.

We know that

S=100 m

The total distance AD=AB + BC+ CD

AD=100 +200 + 100 m

AD=400 m.

The total distance will be 400 m.

answer: the exterior temperature of commercial jet planes as they leave the stratosphere and return to the ground increases steadily.

explanation:

the lower most layer of atmosphere is troposphere which extends from 0 to 12 km above the surface of the earth. the temperature initially decreases as distance is increased from the earth's surface. commercial jets fly in lower part of the stratosphere. the stratosphere extends upto 50 km. the temperature in stratosphere starts rising again due to presence of ozone which traps the uv rays.

thus, when the planes leave the stratosphere and return to the ground, the exterior temperature increases steadily.

c) up

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