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pishuonlain [190]

3 years ago

15

Amy swims 500 m (0.5 Km) in 6 minutes (0.1 hour). What was her speed in Kilometers per hour? A. 8.3 Km/hr B. 5 Km/hr C. 50 Km/hr

D. 83 Km/hr

2 answers:

kondor19780726 [428]3 years ago

8 0

Speed = Distance ÷ Time so divide .5 km by .1h. .5 km÷.1h=5 km/h, so the answer is B. 5km/h.

astra-53 [7]3 years ago

8 0

Speed = Distance/time = 0.5km/0.1 hour = 5 km/hour

Option B.

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A convex lens has a focal length of 16.5 cm. Where on the lens axis should an object be placed in order to get a virtual, enlarg

alexandr402 [8]

Answer:

Object should be placed at a distance, u = 7.8 cm

Given:

focal length of convex lens, F = 16.5 cm

magnification, m = 1.90

Solution:

Magnification of lens, m = - $\frac{v}{u}$

where

u = object distance

v = image distance

Now,

1.90 = $\frac{v}{u}$

v = - 1.90u

To calculate the object distance, u by lens maker formula given by:

$\frac{1}{F} = \frac{1}{u}+ \frac{1}{v}$

$\frac{1}{16.5} = \frac{1}{u}+ \frac{1}{- 1.90u}$

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4 years ago

What is one way to lower gravitational potential energy?

il63 [147K]

Answer:

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Explanation:

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4 0

2 years ago

A truck on a straight road starts from rest, accelerating at 2.00 m/s2 until it reaches a speed of 20.0 m/s. Then the truck trav

aniked [119]

<span>You can use the equation
V_xf = V_xi + a_x(t)

V_xf = 20.0m/s
V_xi = 0m/s
ax = 2.0 t

Thus, solve for t and get 10seconds and then take 5 seconds to break after 20 seconds of driving so for

a) 10 + 20 + 5 = 35 seconds

</span><span>for part b)
You can use the formula
Delta x/Delta t = average velocity

Need to find xf, knowing xi = 0

Thus, use the formula
x_f = x_i + V_xi(t) + (1/2)a_x(t)^(2)
x_f = 0 + 0(10) + (1/2)(2.0)(10)^(2)
x_f = 100m

so for the first 10 seconds the truck traveled 100ms At a speed of 20m/s

20m/s = xm/20s 20*20 = x
x = 400

thus we have 100+400 = 500m then it slows down from 500m to x_f

thus I use the equation
x_f = x_i + (1/2)(V_xf + V_xi)t
x_f = 500 + (1/2)(0 + 20)(5) x_f = 500 + 50
x_f = 550

therefore the total distance traveled is 550m
</span>
<span>to calculate average velocity
550/35 = 16m/s

thus V_xavg = 16m/s</span>

8 0

3 years ago

An ocean wave has a wavelength of 15 meters and is moving at 2.5 m/s. what is the frequency

Tasya [4]

Answer:

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8 0

3 years ago

Read 2 more answers

Approximate the human form as an unclothed vertical cylinder of 0.3 m diameter and 1.75 m length with a surface temperature of 3

Zolol [24]

Answer:

$q=1118.865W$

Explanation:

From the question we are told that

Diameter of the cylinder $D=0.3m$

Length of the cylinder $L=1.75m$

Surface temperature of cylinder $T_s=30 \textdegree C=303k$

Speed of air $V=10m/s$

Temperature of air $T=20 \textdegree C$

Generally the equation for Reynolds number is mathematically given by

$Re_D=\frac{VD}{v}$

where

$v=15.27*10^-^6$

$Re_D=\frac{10*0.3}{15.27*10^-^6}$

$Re_D=1.96*10^5$

Generally the equation for Nusselt number is mathematically given by

$N_u=0.6(Re_D)^{0.6}(Pr)^{0.37}$

where

Prandtl number

$Pr=0.71$

$N_u=0.6(Re_D)^{0.6}(Pr)^{0.37}$

$N_u=0.6(1.96*10^5)^{0.6}(0.71)^{0.37}$

$N_u=791.53$

Generally the equation for convective heat transfer is mathematically given by

$h=Nu \frac{k}{D}$

where

$k=25.7*10^{-3}$

$h=791.53*\frac{25.7*10^{-3}}{0.3}$

$h=67.81W/m^2K$

Generally the equation for surface area of a cylinder is mathematically given by

$A=\pi DL$

$A=\pi *0.3*1.75$

$A=1.65m^2$

Generally the equation for convective heat transfer is mathematically given by

$q=h4(T_s-T_{inty)}$

$q=(67.81)*1.65*(30-20)\\$

$q=1118.865W$

3 0

3 years ago