All categories

3 years ago

If your speed changes from 10 km/h to 6 km/h, you have a(n) ______ acceleration.

2 answers:

8 0

If your speed changes from 10 km/h to 6 km/h then
you have an acceleration.

Whether it's a positive or negative one completely depends
on which direction you decided to call the positive direction,
when you started considering your speed and its changes.

If you decided to call the direction in which you're traveling
the positive direction, then a decrease in your speed is a
negative acceleration.

But you could just as easily have said that you're traveling
in the negative direction. If you did that, then a decrease in
your speed would be a positive acceleration.

It's completely up to you, and how you define things.

Leona [35]3 years ago

7 0

If your speed changes from 10 km/h to 6 km/h, you have a(n) a.negative acceleration.

You might be interested in

Why are red stars cooler than blue stars?

asambeis [7]

OK both stars are burning and as they burn they emit electromagnetic radiation (light) and as we move in the light spectrum red comes before blue, so the star that looks red is cooler because as the temperature decreases the colour decreases

6 0

3 years ago

Read 2 more answers

Yosef is playing with different kinds of rubber bands. Some are very narrow, and some are quite wide. Yosef is curious about the

Cerrena [4.2K]

Answer:

Yosef hypothesis could be stretching of rubber band depends on rubber band's width. It is difficult to stretch a wider rubber band in comparison to a narrow band.

Explanation:

Width of rubber band affect how easily it can be stretched. It is found that it is difficult to to stretch a wider rubber band in comparison to a narrow band because when rubber band is narrow less molecules will be there along its width and hence less restoring force will be there so rubber can be easily stretched. On the other hand when the rubber band is wider it means more molecules are there along its width and hence more restoring force will be there while stretching so it will be difficult to stretch a wider rubber band.

5 0

3 years ago

Read 2 more answers

The initial kinetic energy imparted to a 0.020 kg bullet is 1200 J. (a) Assuming it

Lilit [14]

Answer:

(a) Power= 207.97 kW

(b) Range= 5768.6 meter

Explanation:

Given,

Mass of bullet, $m=0.02 kg$

Kinetic energy imparted, $K=1200 J$

Length of rifle barrel, $d=1 m$

(a)

Let the speed of bullet when it leaves the barrel is $v$ .

Kinetic energy, $K=\frac{1}{2} mv^{2}$

$v=\sqrt{\frac{2K}{m} }$

$=\sqrt{\frac{2\times1200}{0.02} }$

$=346.4m/s$

Initial speed of bullet, $u=0$

The average speed in the barrel, $v_a_v_g=\frac{u+v}{2}$

$=\frac{0+346.4}{2} \\=173.2 m/s$

Time taken by bullet to cross the barrel, $t=\frac{d}{v}$

$=\frac{1}{173.2}\\ =0.00577 second$

Power, $P_a_v_g=\frac{W}{t}$

$=\frac{1200}{0.00577} \\=207.97kW$

(b)

In projectile motion,

Maximum height, $H_m=\frac{v^2\sin^2\theta}{2g} \\$

Range, $R=\frac{v^2\sin2\theta}{g}$

given that, $H_m=R$

then, $\frac{v^2\sin^2\theta}{2g}=\frac{v^2\sin2\theta}{g}\\\sin^2\theta=2\sin\theta\cos\theta\\\\\tan\theta=4\\\theta=\tan^-^14\\\theta=75.96^0\\R=\frac{v^2\sin2\theta}{g}\\=\frac{346.4^2\times\sin(2\times75.96)}{9.8}\\5768.6 meter$

5 0

3 years ago

3) A bird flies toward a tree limb at a 45-degree angle to the ground along a path that is 50 m long landing on the limb. Determ

marin [14]

Answer:

35 m

Explanation:

Given :

The distance of the path from the ground to the tree limb = 50 m

The angle between the path of flight of the bird towards the tree limb and the ground = 45 degrees

Therefore we can determine the height above which the bird perched above the ground by using the rules of the trigonometric ratios as;

We know that ,

$\sin 45^\circ =\frac{\text{perpendicular}}{\text{hypothenus}}$

$\sin 45^\circ =\frac{\text{BC}}{\text{AC}}$

$0.7 =\frac{\text{BC}}{\text{50}}$

$\text{BC }= 0.7 \times 50$

= 35

Therefore, the bird perched on the tree limb at a height of 35 m.

6 0

3 years ago

Would you be more concerned if something you consider precious went through a

Dahasolnce [82]

Answer:

Explanation:

A chemical change.

Usually those are irreversible. Or they may be reversible, but the form they take may leave your object not the same as they started out.

A physical change might be just as deadly. If the object melted like a chocolate Easter Bunny then the object would be irreversible as well. Take a better example.

Suppose you are talking about a Gold Coin. If you heated it so it melted, the gold would retain its value, but the fact that it is a coin and valuable as such, means that it has lost that part of its value.

I really don't know. My instincts tell me that the chemical change is more dangerous, but I can't rule out the other choice..

5 0

2 years ago