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2 years ago

How do scientists know our universe is older than 6500 years?

1 answer:

5 0

This is because astronomers have discovered that the Crab Nebula is 6500 light years from earth. This means it takes 6500 earth years for light to get from the Crab Nebula to earth. Therefore, if we are able to observe the Crab Nebula and beyond it then it means that earth has been in existence for 6500 years and over.

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The auto in the sketch moves forward as the brakes are applied. A bystander says that during the interval of braking, the auto's

Ivan

Answer:

The statement is true: velocity and acceleration have opposite directions in the interval of braking.

Explanation:

Let's say we have a velocity $v>0$ .

The acceleration $a$ is the rate of change of the velocity $v$ . This means that if $v$ is increasing during time, then $a$ must be positive. But if $v$ is decreasing over time, then $a$ will be negative (even though the velocity is positive).

Mathematically:

$a=\frac{dv}{dt}$

$v$ decreases ⇒ $\frac{dv}{dt}$

⇒ $a$ .

Example:

$v(t)=e^{-t}>0 \\\\\frac{dv}{dt}=-te^{-t}$

3 0

2 years ago

12 seconds after starting from rest a frewly falling cantaloupe has a speed of

adoni [48]

Answer:

The cantaloupe has a speed of 117.6 m/s

Explanation:

Free Fall Motion

It occurs when an object falls under the sole influence of gravity. Any object that is being acted upon solely by the force of gravity is said to be in a state of free fall. Free-falling objects do not face air resistance.

If an object is dropped from rest in a free-falling motion, it falls with a constant acceleration called the acceleration of gravity, which value is $g = 9.8 m/s^2$ .

The final velocity of a free-falling object after a time t is given by:

vf=g.t

The cantaloupe has been dropped from rest. We are required to find the speed after t=12 seconds.

Calculate the final speed:

vf=9.8 * 12 = 117.6 m/s

The cantaloupe has a speed of 117.6 m/s

3 0

2 years ago

A 1.0kg ball has a momentum of 12kg m/s what is the balls speed

Anastasy [175]

The momentum of an object is given by:
$p=mv$
where
p is the momentum
m is the mass
v is the velocity of the object

The ball in our problem has a mass of m=1.0 kg and a momentum of $p=12 kg m/s$ , therefore we can use the previous formula to find its velocity:
$v= \frac{p}{m}= \frac{12 kg m/s}{1.0 kg}=12 m/s$

8 0

2 years ago

You and your bicycle have combined mass 80.0 kg. When you reach the base of a bridge, you are travelling along the road at 7.50

Sonja [21]

We have that K.E and work done is