A train travels 80 kilometers in 2 hours, and then 79 kilometers in 4 hours. What is its average speed?

Select the correct answer. Which healthy snack can provide protein after physical activity? A. an orange slice B. pretzels C. yo

givi [52]

Answer:

From the given choices, the healthy snack that can provide protein after physical activity is the third option, yogurt. Yogurts are derived from fermentation of raw materials by the healthy bacteria, usually of lactobacillus origin. Other items in the choices are not able to provide protein.

Explanation:

4 0

3 years ago

Finding the spring constant as shown, spring 3, which has an unknown spring constant k3, replaces spring 2. the mass of the weig

nevsk [136]

Replaces spring 2. the mass of the weight and pulley are unchanged: m=5.8 kg and mp=1.7 kg

6 0

4 years ago

Which of theses substances would be a poor conductor of electricity

lys-0071 [83]

Answer:

B. Water and sugar.

Explanation:

In the given options water and sugar would be the poor conductor of electricity. Other given options such as water and salt, water and Hcl and water and NaOH are better conductor of electricity because Hcl ,NaOH, salt (Nacl) can break into their ionic form whereas water and sugar will not.

8 0

4 years ago

The electrons in the beam of a television tube have a kinetic energy of 2.20 10-15 j. initially, the electrons move horizontally

dalvyx [7]

(a) The electrons move horizontally from west to east, while the magnetic field is directed downward, toward the surface. We can determine the direction of the force on the electron by using the right-hand rule:
- index finger: velocity --> due east
- middle finger: magnetic field --> downward
- thumb: force --> due north
However, we have to take into account that the electron has negative charge, therefore we have to take the opposite direction: so, the magnetic force is directed southwards, and the electrons are deflected due south.

b) From the kinetic energy of the electrons, we can find their velocity by using
$K= \frac{1}{2}mv^2$
where K is the kinetic energy, m the electron mass and v their velocity. Re-arranging the formula, we find
$v= \sqrt{ \frac{2K}{m} }= \sqrt{ \frac{2 \cdot 2.20 \cdot 10^{-15} J}{9.1 \cdot 10^{-31} kg} }=6.95 \cdot 10^7 m/s$

The Lorentz force due to the magnetic field provides the centripetal force that deflects the electrons:
$qvB = m \frac{v^2}{r}$
where
q is the electron charge
v is the speed
B is the magnetic field strength
m is the electron mass
r is the radius of the trajectory
By re-arranging the equation, we find the radius r:
$r= \frac{mv}{qB}= \frac{(9.1 \cdot 10^{-31} kg)(6.95 \cdot 10^7 m/s)}{(1.6 \cdot 10^{-19} C)(3.00 \cdot 10^{-5} T)}=13.18 m$

And finally we can calculate the centripetal acceleration, given by:
$a_c = \frac{v^2}{r}= \frac{(6.95 \cdot 10^7 m/s)^2}{13.18 m}=3.66 \cdot 10^{14} m/s^2$

5 0

3 years ago

Every complete circuit includes a device that provides emf. What type of quantity?

laiz [17]

Answer:

energy per unit charge

Explanation:

EMF is energy per unit charge and has unit joule/ coulomb, where joule is unit of energy and coulomb is the unit of charge.

6 0

3 years ago