That depends on the wavelength of the electromagnetic radiation.
-- If the waves are long, then we use them for radio, TV, and cellphones.
-- If the waves are shorter than that, then we use them for GPS in the car.
-- If the waves are shorter than that, then we use them to heat meatloaf
in the microwave oven.
-- If the waves are shorter than that, then they warm us and they
make our plants grow ... like the ones we eat.
-- If the waves are shorter than that, then our eyes use them to see with.
-- If the waves are shorter than that, then they tan our skin.
-- If the waves are shorter than that, then they can cause cancer on
our skin.
-- If the waves are shorter than that, then they can cause cancer and
other diseases in places inside our body.
Answer:
41.0 m/s, 10.6 s
Explanation:
Given:
a = -4.8 m/s²
Δy = 165 m
v = -10.0 m/s
Find: v₀ and t
v² = v₀² + 2aΔy
(-10.0 m/s)² = v₀² + 2(-4.8 m/s²) (165 m)
v₀ = 41.0 m/s
Δy = vt − ½ at²
165 m = (-10.0 m/s) t − ½ (-4.8 m/s²) t²
165 = -10t + 2.4t²
0 = 2.4t² − 10t − 165
Solve with quadratic formula:
t = [ -(-10) ± √((-10)² − 4(2.4)(-165)) ] / 2(2.4)
t = (10 ± √1684) / 4.8
t = 10.6 s
Answer:
(a) 5.7 s
(b) 39 m/s
Explanation:
(a) u = 18 m/s
At the maximum height, the final velocity of ball is zero. lte teh time taken by the ball to go from 50 m height to maximum height is t.
use first equation of motion.
v = u + g t
0 = 18 - 10 x t
t = 1.8 s
Let the maximum height attained by the ball when it thrown from 50 m height is h'.
Use third equation of motion
v^2 = u^2 + 2 g h'
0 = 18^2 - 2 x 10 x h'
h' = 16.2 m
Total height from the ground H = h + h' = 50 + 16.2 = 76.2 m
Let t' be the time taken by the ball to hit the ground as it falls from maximum height.
use third equation of motion
H = ut + 1/2 x g t'^2
76.2 = 0 + 1/2 x 10 x t'^2
t' = 3.9 s
Total time taken by the ball to hit the ground = T = t + t' = 1.8 + 3.9 = 5.7 s
(b) Let v be the velocity with which the ball strikes the ground.
v^2 = u^2 + 2 g H
v^2 = 0 + 2 x 10 x 76.2
v = 39 m/s
Answer:
angle is 19.85°
Explanation:
given data
grade = 36.1 %
vertically distance y = 36.1 m
horizontal distance x = 100 m
to find out
angle
solution
we know that according to question here
it make a triangle shape that contain 100 m base and height 36.1 m
and make angle with base is θ
so by triangle we know here
tanθ = y/x ..........1
so we now put x and y and find θ
tanθ = 36.1 / 100
tanθ = 0.361
θ = 19.85°
so angle is 19.85°
