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4 years ago

6

A car starts from rest and after 7 seconds it is moving at 42 m/s. What is the car’s average acceleration? A. 0.17 m/s2 B. 1.67

m/s2 C. 6 m/s2 D. 7 m/s2 E. none of the above

2 answers:

aliya0001 [1]4 years ago

5 0

Acceleration =velocity /time
=42/7
=6

tamaranim1 [39]4 years ago

4 0

C. 6 m/s2 is correct

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In the two-slit experiment, for the condition of bright fringes, the value of m = +2 corresponds to a path difference of λ.

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False

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3 years ago

A rocket is fired vertically upwards with initial velocity 92 m/s at the ground level. Its engines then fire and it is accelerat

Readme [11.4K]

Answer:

The rocket above the ground is in 44 sec.

Explanation:

Given that,

Initial velocity = 92 m/s

Acceleration = 4 m/s²

Altitude = 1200 m

Suppose, How long was the rocket above the ground?

We need to calculate the time

Using equation of motion

$s=ut-\dfrac{1}{2}at^2$

Put the value into the formula

$1200=92t+\dfrac{1}{2}\times4t^2$

$2t^2+92-1200=0$

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We need to calculate the velocity

Using equation of motion

$v=u+at$

Put the value into the formula

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When the rocket hits the ground,

Then, h'=0

We need to calculate the time

Using equation of motion

$h'=h+ut-\dfrac{1}{2}at^2$

Put the value into the formula

$0=1200+132t-\dfrac{1}{2}\times9.8t^2$

$4.9t^2-132t-1200=0$

$t=34\ sec$

When the rocket is in the air it is the sum of the time when it reaches 1000 m and the time when it hits the ground

So, the total time will be

$t'=34+10$

$t'=44\ sec$

Hence, The rocket above the ground is in 44 sec.

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4 years ago