The ball was kicked with a speed of 38.4 m/s.
Using s = ut + 1/2gt², we find the time it takes the ball to reach the ground. Where
- s = height of cliff = 75 m
- u = <u>initial</u> vertical velocity of ball = 0 m/s(since it is kicked horizontally)
- g = acceleration due to gravity = 9.8 m/s²
- t = time taken for ball to reach the ground.
Substituting the values of the variables into the equation, we have
s = ut + 1/2gt²
75 m = (0 m/s)t + 1/2 × 9.8 m/s² × t²
75 m = 0 m + (4.9 m/s²) t²
75 m = (4.9 m/s²)t²
Dividing both sides by 4.9, we have
t² = 75 m/4.9 m/s²
t² = 15.306 s²
Taking square-root of both sides, we have
t = √15.306 s²
t = 3.91 s
The horizontal distance covered by the ball d = vt where
- v = <u>horizontal</u> speed of ball and,
- t = time taken for the ball to reach the ground.
Since we require v, we make it subject of the formula.
So, v = d/t
Given that d = 150 m and t = 3.91 s, substituting these into v, we have
v = d/t
v = 150 m/3.91 s
v = 38.4 m/s
So, the ball was kicked with a speed of 38.4 m/s.
Learn more about motion under gravity here:
brainly.com/question/25271752
Devonshire Street telescopes how are earths telescopes that’s all me Siri you are I go to the store area
Answer:
0.2 m/s
Explanation:
given,
mass of astronaut, M = 85 Kg
mass of hammer, m = 1 Kg
velocity of hammer , v =17 m/s
speed of astronaut, v' = ?
initial speed of the astronaut and the hammer be equal to zero = ?
Using conservation of momentum
(M + m) V = M v' + m v
(M + m) x 0 = 85 x v' + 1 x 17
85 v' = -17
v' = -0.2 m/s
negative sign represent the astronaut is moving in opposite direction of hammer.
Hence, the speed of the astronaut is equal to 0.2 m/s
The frequency of a beam of light does not change as it passes from a medium to another, only its wavelength and speed are affected. The experimental speed of light in air is:
3 * 10^8 m/s
Therefore, the frequency of this beam of light is:
v = fλ; where v is speed, f is frequency, and λ is the wavelength. The frequency thus is:
3×10⁸ / (670 × 10⁻⁹) = 4.48 × 10¹⁴ Hz
The frequency will remain the same in the solid medium
The speed will then become:
4.48 × 10¹⁴ × 420 × 10⁻⁹ = 1.88 × 10⁸ meters per second
