Average speed=total distance traveled/time. Total distance=the sum of the two short distances=79*2+77*3=389 km. Total time used to travel is 2+3=5 hr. Average speed is 389/5=77.8 km/hr.
Answer:
light doesn't need a medium through which to travel because the speed of light is experimentally constant
Answer:
The time taken to stop the box equals 1.33 seconds.
Explanation:
Since frictional force always acts opposite to the motion of the box we can find the acceleration that the force produces using newton's second law of motion as shown below:

Given mass of box = 5.0 kg
Frictional force = 30 N
thus

Now to find the time that the box requires to stop can be calculated by first equation of kinematics
The box will stop when it's final velocity becomes zero

Here acceleration is taken as negative since it opposes the motion of the box since frictional force always opposes motion.
Answer: 31.33 degrees
Explanation:
The diffraction angles
when we have a slit divided into
parts are obtained by the following equation:
(1)
Where:
is the width of the slit
is the wavelength of the light
is an integer different from zero.
Now, the first-order diffraction angle is given when
, hence equation (1) becomes:
(2)
Now we have to find the value of
:
(3)
We know:

In addition we are told the diffraction grating has 5000 slits per mm, this means:

Substituting the known values in (3):


<u>Finally:</u>
>>>This is the first-order diffraction angle