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3 years ago

A school custodian waxed a gymnasium floor that measured 20 feet by 20 feet. How many square feet did she have to wax?

1 answer:

5 0

We have to calculate how many square feet a school custodian has to wax and to choose the correct answer. A gymnasium floor is in the shape of the square ( 20 by 20 feet ). The area of the square is : A = L^2. For L = 20 ft, A = 20^2 = 20 * 20 = 400 ft^2. Answer: D. 400 square feet.

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A proton is accelerated from rest through a potential difference of 2.5 kV and then moves perpendicularly through a uniform 0.60

Bumek [7]

Answer:

1.2cm

Explanation:

V=(2ev/m)^1/2

=(2*1.6*10^19 x2500/ 1.67*10^27)^1/2

=6.2x10^5m/s

Radius of resulting path= MV/qB

= 1.67*10^-27x6.92*10^6/1.6*10^-16 x0.6

=0.012m

=1.2cm

5 0

3 years ago

Read 2 more answers

Select all that apply. Which of the following astronomers supported the Earth-centered system?

Stella [2.4K]

Among the options, the two astronomers who supported the Earth-centered system were Tycho Brahe and Ptolemy.

Both astronomers developed in fact a system where the Sun was located at the center, while the Earth and the other planets were orbiting around the Sun.

6 0

3 years ago

Read 2 more answers

Set the radius to 2.0 m and the velocity to 1.0 m/s. Keeping the radius the same, record the magnitude of centripetal accelerati

jek_recluse [69]

Answer:

$a=4\ m/s^2$

Explanation:

Given that,

Radius, r = 2 m

Velocity, v = 1 m/s

We need to find the magnitude of the centripetal acceleration. The formula for the centripetal acceleration is given by :

$a=\dfrac{v^2}{r}\\\\a=\dfrac{(2)^2}{1}\\\\=4\ m/s^2$

So, the magnitude of centripetal acceleration is $4\ m/s^2$ .

5 0

2 years ago

A car moves uphill at 40 km/h and then back downhill at 60 km/h. What is the average speed for the round trip?

jok3333 [9.3K]

Answer:

$S_a_v_e_r_a_g_e=48km/h$

Explanation:

Ok, the average speed can be calculate with the next equation:

$S_a_v_e_r_a_g_e=\frac{Total\hspace{3}distance}{Total\hspace{3}time}$ (1)

Basically the car cover the same distance "d" two times, but at different speeds, so:

$Total\hspace{3}distance=2*d$

and the total time would be the time t1 required to go from A to B plus the time t2 required to go back from B to A:

$Total\hspace{3}time=t1+t2$

From basic physics we know:

$t=\frac{d}{S1}$

so:

$t1=\frac{d}{S1}$

$t2=\frac{d}{S2}$

Using the previous information in equation (1)

$S_a_v_e_r_a_g_e=\frac{2*d}{\frac{d}{S1} +\frac{d}{S2} }=\frac{2*d}{\frac{d*S2+d*S1}{S1+S2} }$

Factoring:

$S_a_v_e_r_a_g_e=\frac{2*S1*S2}{S1+S2}$ (2)

Finally, replacing the data in (2)

$S_a_v_e_r_a_g_e=\frac{2*40*60}{60+40} =48km/h$

5 0

3 years ago

Two +1 C charges are separated by 30000 m, what is the magnitude of the force?

Kipish [7]

Answer:

The magnitude of the force is 10 N

Explanation:

Coulomb's Law

The electrostatic force between two charged objects is directly proportional to the product of their charges and inversely proportional to the square of the distance between the two objects.

Written as a formula:

$\displaystyle F=k\frac{q_1q_2}{d^2}$