Answer: 2940 J
Explanation: solution attached:
PE= mgh
Substitute the values:
PE= 10kg x 9.8 m/s² x 30 m
= 2940 J
<u>Answer:</u> The ball is travelling with a speed of 5.5 m/s after hitting the <u>bottle.</u>
<u>Explanation:</u>
To calculate the speed of ball after the collision, we use the equation of law of conservation of momentum, which is given by:

where,
are the mass, initial velocity and final velocity of ball.
are the mass, initial velocity and final velocity of bottle.
We are given:

Putting values in above equation, we get:

Hence, the ball is travelling with a speed of 5.5 m/s after hitting the bottle.
Answer:
D) directly, inversely
Explanation:
The energy of a photon of light is directly proportional to its frequency and inversely proportional to its wavelength.
Frequency is the number of waves that passes through a point per unit of time.
Wavelength is the is the distance between successive crests or troughs on a wave.
Mathematically, frequency is related to wavelength and velocity using;
Energy = h x f
where h is the Planck's constant
f is the frequency
Since c = f ∧
where f is the frequency of the wave
∧ is the wavelength of the wave
c is the speed of light
So;
f = c/∧
Therefore;
E = 
From the equation, we see an inverse relationship between E and wavelength and a direct one with frequency.