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Vedmedyk [2.9K]
3 years ago
5

John is traveling north at 20 meters/second and his friend Betty is traveling south at 20 meters/second. If north is the positiv

e direction, what are John and Betty's speeds? A. -20 meters/second, 20 meters/second B. 20 meters/second, 20 meters/second C. -20 meters/second, -20 meters/second D. 0 meters/second, 40 meters/second
Physics
2 answers:
soldier1979 [14.2K]3 years ago
8 0
The answer is definitely A
rewona [7]3 years ago
7 0

Answer:

B. 20 meters/second, 20 meters/second

Explanation:

Velocity of John = 20 meters/second north = +20 meters/second

Velocity of Betty =  20 meters/second south = -20 meters/second

If north is considered as positive then south will be negative.

So, the velocity of John will be +20 meters/second and velocity of Betty will be -20 meters/second.

But, the question is about their speeds and not velocity. The signs represent the directions. Speed does not show direction.

So, speed of John and Betty is 20 meters/second.

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Temperature flows from __ to __ temperatures
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Answer:hot to cold

Explanation:

Temperature flow from hot to cold temperatures

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The wires in a household lamp cord are typically 3.5 mm apart center to center and carry equal currents in opposite directions.
zhuklara [117]

Explanation:

It is given that,

Distance between wires, d = 3.5 mm = 0.0035 m

Power of light bulb, P = 100 W

Potential difference, V = 120 V

(a) We need to find the force per unit length each wire of the cord exert on the other. It is given by :

\dfrac{F}{l}=\dfrac{\mu_o I^2}{2\pi r}

Power, P = V × I

I=\dfrac{P}{V}=\dfrac{100}{120}=0.83\ A

This gives, \dfrac{F}{l}=\dfrac{4\pi \times 10^{-7}\times (0.83)^2}{2\pi \times 0.0035}

\dfrac{F}{l}=0.0000393\ N/m

\dfrac{F}{l}=3.93\times 10^{-5}\ N/m

(b) Since, the two wires carry equal currents in opposite directions. So, teh force is repulsive.

(c) This force is negligible.

Hence, this is the required solution.

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3 years ago
What is called the process of finding exact quantity of a substance?​
Tema [17]

Answer:

Measurement is called the process of finding exact quantity of a substances.

7 0
2 years ago
An object with more mass has more kinetic energy than an object with less mass, if both objects are moving ____.
suter [353]

An object with more mass has more kinetic energy than an object with less mass, if both objects are moving at the same speed. <em>(c)</em>

6 0
3 years ago
Read 2 more answers
Determine the magnitude of the resultant force acting on a 1.5 −kg particle at the instant t=2 s, if the particle is moving alon
Phoenix [80]

Answer:

F = 63N

Explanation:

M= 1.5kg , t= 2s, r = (2t + 10)m and

Θ = (1.5t² - 6t).

magnitude of the resultant force acting on 1.5kg = ?

Force acting on the mass =

∑Fr =MAr

Fr = m(∇r² - rθ²) ..........equation (i)

∑Fθ = MAθ = M(d²θ/dr + 2dθ/dr) ......... equation (ii)

The horizontal path is defined as

r = (2t + 10)

dr/dt = 2, d²r/dt² = 0

Angle Θ is defined by

θ = (1.5t² - 6t)

dθ/dt = 3t, d²θ/dt² = 3

at t = 2

r = (2t + 10) = (2*(2) +10) = 14

but dr/dt = 2m/s and d²r/dt² = 0m/s

θ = (1.5(2)² - 6(2) ) = -6rads

dθ/dt =3(2) - 6 = 0rads

d²θ/dt = 3rad/s²

substituting equation i into equation ii,

Fr = M(d²r/dt² + rdθ/dt) = 1.5 (0-0)

∑F = m[rd²θ/dt² + 2dr/dt * dθ/dt]

∑F = 1.5(14*3+0) = 63N

F = √(Fr² +FΘ²) = √(0² + 63²) = 63N

7 0
3 years ago
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