Name three elements that have similar chemical properties to oxygen

A driver spotted a police car and he braked from a speed of 100 km/h to a speed of 80 km/h during a displacement of 88 m at a co

jek_recluse [69]

Answer:

Explanation:

100 kph = 27.8 m/s

80 kph = 22.2 m/s

v² = u² + 2as

a = (v² - u²) / 2s

a = (22.2² - 27.8²) / (2(88))

a = -1.578282828...

a = -1.58 m/s²

t negative sign means the acceleration opposes the initial velocity.

t = Δv/a

t = (22.2 - 27.8) / -1.57828

t = 3.52 s

3 0

3 years ago

A boy im50kg at rest on a skateboard is pushed by another boy who exerts a force of 200 N on him. If the first boy's

sergey [27]

Answer:

Time, t = 2 seconds

Explanation:

Given the following data;

Mass, m = 50 kg

Initial velocity, u = 0 m/s (since it's starting from rest).

Final velocity, v = 8 m/s

Force, F = 200 N

To find the time, we would use the following formula;

$F = \frac {m(v - u)}{t}$

Making time, t the subject of formula, we have;

$t = \frac {m(v - u)}{F}$

Substituting into the formula, we have;

$t = \frac {50(8 - 0)}{200}$

$t = \frac {50*(8)}{200}$

$t = \frac {400}{200}$

Time, t = 2 seconds

5 0

3 years ago

A standard 12 V car battery has an ampere-hour rating of 40 Ah, whereas a heavy-duty battery has a rating of 60 Ah. How would yo

stiv31 [10]

Answer:

Explanation:

Ah is a unit of charge .

A battery with 12 V and charge capacity of 40 Ah will have energy content

= volt x charge

volt = 12 V

Charge = 40 Ah

= 40 x 60 x 60 A.s

= 144000 coulomb

energy content = 12 x 144000

= 1728000 J

energy content of heavy duty battery

= 12 x 60 x 60 x 60

= 2592000 J

Ratio = 1728000 / 2592000

= 2 / 3

Current can not be compared as current depends upon the resistance of appliance used . As resistance of appliance is unknown , current can not be compared.

3 0

4 years ago

Particle moves in a circle of radius 90m with a constant speed 25m/s. how many revolution does it make in 30sec

Serggg [28]

Answer:

<em>n =1.33 revolutions</em>

Explanation:

<u>Uniform Circular Motion</u>

The angular speed can be calculated in two different ways:

$\displaystyle \omega=\frac{v}{r}$

Where:

v = tangential speed

r = radius of the circle described by the rotating object

Also:

$\omega=2\pi f$

Where:

f = frequency

Solving for f:

$\displaystyle f=\frac{\omega}{2\pi}$

Since the frequency is calculated when the number of revolutions n and the time t are known:

$\displaystyle f=\frac{n}{t}$

We can solve for n:

n=f.t

The particle moves in a circle of r=90 m with a speed v=25 m/s. Thus the angular speed is:

$\displaystyle \omega=\frac{25}{90}$

$\displaystyle \omega=0.278\ rad/s$

Now we calculate f:

$\displaystyle f=\frac{0.278}{2\pi}$

$f=0.04421\ Hz$

Calculating the number of revolutions:

n = 0.04421*30

n =1.33 revolutions

8 0

3 years ago

What would happen if earth was further from the sun

Colt1911 [192]

Earth would have different climates and would be more colder.

3 0

3 years ago

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