Answer:
option B
Explanation:
given,
height of building = 0.1 km
ball strikes horizontally to ground at = 65 m
speed at which the ball strike = ?
vertical velocity = 0 m/s
time at which the ball strike



t = 4.53 s
vertical velocity at the time 4.53 s = g × t = 9.8 × 4.53 = 44.39 m/s
horizontal velocity =
=14.35 m/s
speed of the ball =
= 46.65 m/s
hence, the speed of the ball just before it strike the ground = 47 m/s
The correct answer is option B
Answer:
r₂ = 0.2 m
Explanation:
given,
distance = 20 m
sound of average whisper = 30 dB
distance moved closer = ?
new frequency = 80 dB
using formula

I₀ = 10⁻¹² W/m²
now,



to hear the whisper sound = 80 dB



we know intensity of sound is inversely proportional to square of distances



r₂ = 0.2 m
The relationship between frequency and wavelength for an electromagnetic wave is

where
f is the frequency

is the wavelength

is the speed of light.
For the light in our problem, the frequency is

, so its wavelength is (re-arranging the previous formula)
I believe that the answer to this would be B
Hope this helped
Mass is the amount of matter in a material while weight is a measure of how the force of gravity acts upon the mass.