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1 year ago

7

An electric heater has a power rating of 800W. If the total energy used by the electric heater is 480kj, how long was the heater

on for?
A.0.6 seconds
B.10 minutes
C.1.67 seconds
D.60 minutes

1 answer:

maks197457 [2]1 year ago

6 0

So basically I think c is the right answer

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A police car is traveling north on a straight road at a constant 16.0 m/s. An SUV traveling north at 30.0 m/s passes the police

Nastasia [14]

Answer:

It will take 15.55s for the police car to pass the SUV

Explanation:

We first have to establish that both the police car and the SUV will travel the same distance in the same amount of time. The police car is moving at constant velocity and the SUV is experiencing a deceleration. Thus we will use two distance fromulas (for constant and accelerated motions) with the same variable for t and x:

1. $x=x_{0}+vt$

2. $x=x_{0}+v_{0}t+\frac{at^{2}}{2}$

Since both cars will travel the same distance x, we can equal both formulas and solve for t:

$vt = v_{0}t+\frac{at^2}{2}\\\\ 16\frac{m}{s}t =30\frac{m}{s}t-\frac{1.8\frac{m}{s^{2}} t^{2}}{2}$

We simplify the fraction present and rearrange for our formula so that it equals 0:

$0.9\frac{m}{s^{2}} t^{2}-14\frac{m}{s}t=0 \\\\ t(0.9\frac{m}{s^{2}}t-14\frac{m}{s})=0$

In the very last step we factored a common factor t. There is two possible solutions to the equation at $t=0$ and:

$0.9\frac{m}{s^{2}}t-14\frac{m}{s}=0 \\\\ 0.9\frac{m}{s^{2}}t =14\frac{m}{s} \\\\ t =\frac{14\frac{m}{s}}{0.9\frac{m}{s^{2}}}=15.56s$

What this means is that during the displacement of the police car and SUV, there will be two moments in time where they will be next to each other; at $t=0 s$ (when the SUV passed the police car) and $t=15.56s$ (when the police car catches up to the SUV)

8 0

2 years ago

A ball is tossed straight up from the surface of a small, spherical asteroid with no atmosphere. The ball rises to a height equa

alukav5142 [94]

Answer:

d. equal to one-fourth the acceleration at the surface of the asteroid.

Explanation:

The explanation is attached as a picture with this answer

Newton's law of universal gravitation is being used to compare the accelerations at the surface and at the top of the ball's path.

as it can be seen in the explanation that the proportional form of the equation is used because we do not need to necessarily use to final form with "G" for comparison calculations.

As per the given scenario only difference between the two points in the gravitational field is the distance from center of the spherical asteroid, i.e. r.

It is taken 2r for the top is the path. hence we obtain (1/4)g as our answer.

4 0

3 years ago

Read 2 more answers

Find the difference between two masses measured as 123.6 grams and 115.972 grams. Express the answer to the correct number of si

xxTIMURxx [149]

Answer:

The difference is 7.6 grams.

Explanation:

In mathematics the difference of two numbers is express as the subtraction between them:

$a-b$

So to find out the difference between the two measured masses, a will be represented by 123.6 grams since is the bigger number, and b by 115.972 grams.

Therefore, it is get:

$123.6grams-115.972grams = 7.6grams$

<u>Hence, the difference is 7.6 grams. </u>

The result of 7.628 will be expressed as 7.6 to have the correct number of significant figures.

Notice how that can be express in units of kilograms too since there is 1000 gram in 1 kilogram:

$7.6grams . \frac{1Kg}{1000grams}$ ⇒ $7.6x10^{-3}Kg$

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2 years ago

Acceleration is the magnitude of average velocity.

lina2011 [118]

Answer:

false

Explanation:

just did the question on apex, true was wrong

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2 years ago

Volume of an block is 5 cm3. If the density of the block is 250 g/cm3, what is the mass of the block ?

9966 [12]

Answer:

1.25kg

Explanation:

Simply multiply volume and density together

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2 years ago