How will you define motion?

Prof. Kopp is working on an experiment located in an abandoned mine near Duluth, MN. The experiment is located approximately 713

MA_775_DIABLO [31]

Answer:

The average speed of the elevator going down in the abandoned mine is 17.722mph.

Explanation:

If the elevator takes 90 seconds to descend a height of 713m, the average speed of the elevator is:

$v_{av}=x_T/t_T=713m/90s=7.922m/s$

And if 1m/s is 2.23694mph, the average speed is:

$v_{av}=7.922m/s=17.722mph$ .

8 0

3 years ago

What is a penalty stroke in field hockey?

Paha777 [63]

Answer: D

Explanation: Because the orginal Penalty stroke is Today's field hockey topic is the exciting penalty stroke! What is a stroke? A penalty stroke occurs when an intentional foul happens in the penalty circle (the circle around the goal), the foul prevents a scoring of a opportunity.

4 0

2 years ago

Read 2 more answers

Consider a 30-cm-diameter hemispherical enclosure. The dome is maintained at 600 K, and heat is supplied from the dome at a rate

SIZIF [17.4K]

Answer:

$\epsilon_2=0.098$

Explanation:

Diameter $d=30cm=0.3m$

Temperature $T=600k$

Rate of supply $r=65W$

Emissivity of base surface $\in_b =0.55$

Temperature at base $T_b=400k$

Generally the equation for Area of base surface is mathematically given by

$A_b=\frac{\pi}{4}d^2$

$A_b=\frac{\pi}{4}0.3^2$

$A_b=0.0707m^2$

Generally the equation for Area of Hemispherical dome is mathematically given by

$A_h=\frac{\pi}{2}d^2$

$A_h=\frac{\pi}{2}0.3^2$

$A_h=0.1414m^2$

Since base is a flat surface

$F_{11}+F_{12}=1$

$F_{11}=0$

Therefore

$F_{12}=1$

$A_b=0.0707m^2$

Generally the equation for Net rate of radiation heat transfer between two surfaces is mathematically given by

$Q_{21}=-Q_{12}$

$Q_{21}=\frac{\sigma(T_1^4-T_2^4)}{\frac{1-\epsilon}{A_b\epsilon_1} +\frac{1}{A_bF_{12}} +\frac{1-\epsilon_2}{A_h*\epsilon_2} }$

Where

$\sigma=5.67*10^{-8}$

Therefore

$65=\frac{(5.67*10^{-8}(400^4-600^4))}{\frac{1-0.55}{0.0707*0.55}+\frac{1}{0.0707}+\frac{1-\epsilon_2}{0.1414*\epsilon_2}}$

$\epsilon_2=0.098$

$\epsilon_2 \approx 0.1$

Therefore the emissivity of the dome is

$\epsilon_2=0.098$

3 0

2 years ago

What is the fastest the block can be spun at without breaking with the block weighing 10kg and spinning horizontally with a 2m s

larisa86 [58]

The fastest speed before the string breaks is 9.5 m/s

Explanation:

The motion of the block is a uniform circular motion, which is a circular motion with constant speed. The force that keeps the block in circular motion is called centripetal force; its direction is towards the centre of the circle and its magnitude is given by:

$F=m\frac{v^2}{r}$