Answer:
Average speed of Elain = 60 km/h
Explanation:
Total Distance covered by Jack = 360km
Average Speed of Jack = 80 km/h
Time taken by Jack to complete his journey = Distance / Average speed = 360 km / 80 km/h
Time taken by Jack to complete his journey = 4.5 hours
As it is given the both Jack and Elain travelled the same amount of distance:
Total distance travelled by Elain = 360 km
It is given that Elain took 1.5 hourse more than Jack to cover the distance, so Time taken by Elain to cover the distance is = 4.5 hours + 1.5 hours = 6 hours
Average speed of Elain = Distance/ time = 360 km / 6 hours
Average speed of Elain = 60 km/h
Wavelength of X-rays = 10⁻¹⁰ m
Wavelength of UV = 1000 x 10⁻¹⁰
= 10⁻⁷ m
Answer:

Explanation:
In order to solve this problem, we mus start by drawing a free body diagram of the given situation (See attached picture).
From the free body diagram we can now do a sum of forces in the x and y direction. Let's start with the y-direction:



so:

now we can go ahead and do a sum of forces in the x-direction:

the sum of forces in x is 0 because it's moving at a constant speed.



so now we solve for theta. We can start by factoring mg so we get:

we can divide both sides into mg so we get:

this tells us that the problem is independent of the mass of the object.

we now divide both sides of the equation into
so we get:


so we now take the inverse function of tan to get:

so now we can find our angle:

so
