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2 years ago

What is the acceleration experienced by a car that takes 10s to reach 27m/s from rest

1 answer:

5 0

|acceleration| = (change in speed) / (time for the change)

Change in the car's speed = (27 - 0) = 27 m/s
Time for the change = 10 sec

|acceleration| = (27 m/s) / (10 s) = 2.7 m/s² .

That's the magnitude of the car's acceleration.
We don't know anything about its direction.

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Compare an Earth year to a cosmic year

sweet-ann [11.9K]

Compared with an Earth year, a galactic year represents time on a grand scale but its not a consistent measurement across the galaxy

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2 years ago

If the cross-section of a wire of fixed length is doubled, how does the resistance of that wire change? A. Halved. B. Doubled C.

Vinil7 [7]

(B)It would get doubled.

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2 years ago

A ball is projected horizontally from the top of a bertical building 25.0m above the ground level with an initial velocity of 8.

kirill115 [55]

Answer:

Solution given:

height [H]=25m

initial velocity [u]=8.25m/s

g=9.8m/s

now;

a. How long is the ball in flight before striking the ground?

Time of flight =?

Now

Time of flight= $\sqrt{\frac{2H}{g}}$

substituting value

= $\sqrt{\frac{2*25}{9.8}}$
=2.26seconds

<h3>the ball is in flight before striking the ground for 2.26seconds.</h3>

b. How far from the building does the ball strike the ground?

Horizontal range=?

we have

Horizontal range=u* $\sqrt{\frac{2H}{g}}$

=8.25*2.26
=18.63m

<h3>The ball strikes 18.63m far from building. </h3>

7 0

2 years ago

A 2 kg ball is moving 3 m/s when it starts rolling up a hill.

AURORKA [14]

Answer:

the height reached is = 0.458 [m]

Explanation:

We need to make a sketch of the ball and see the location of the reference point where the potential energy is zero. But the kinetic energy will be defined by the following expression:

$Ek=\frac{1}{2} *m*v^{2} \\where:Ek= kinetic energy [J]\\m = mass of the ball [kg]\\v = velocity of the ball [m/s]$

Replacing the values on the equation we have:

$Ek=\frac{1}{2}*(2)*(3^{2} )\\ Ek=9[J]\\$

This kinetic energy will be transformed in potential energy in the moment when the ball starts to rolling up. Therefore the maximum height reached by the ball depends of the initial velocity given to the ball.

$Ek=Ep\\where\\Ep=potential energy [J]\\Ep=m*g*h\\where\\g=gravity = 9.81[m/s^2]\\h=height reached [m]\\$

Now we have:

$h=\frac{Ep}{m*g} \\h=\frac{9}{2*9.81} \\\\h=0.45 [m]$

In that moment when the ball reach the 0.45 [m] the potencial energy will be maximum and equal to the kinetic energy when the ball has a velocity of 3[m/s]

6 0

2 years ago

0.002 written in scientific notation

Oliga [24]

Answer:0,002 = 2 x 10⁻³

Explanation:

0,002 = 2 / 1000 = 2 / 10³ = 2 x 10⁻³

3 0

3 years ago