I’d say two soccer balls that are touching each other, I hope that helps!
The position of an oscillating mass is given by:
where A is the amplitude of the oscillation, 
the angular frequency and t the time.
The velocity of the oscillating mass can be found by calculating the derivative of the position:
In this problem, A=2.0 cm and 
, so if we substitute these data and t=0.4 s we can find the velocity at t=0.4 s:
Answer:
6.65m/s
Explanation:
Using the equation of motion
S = ut + 1/2gt²
S is the height of fall
t is the time
u is the horizontal velocity
g is the acceleration due to gravity
Given
S = 300 + 50
S = 350m
t = 7.8seconds
g = 9.8m/s^2
Get S
S = 7.8u + 1/2(9.8)(7.8)²
S = 7.8u + 298.116
350 = 7.8u + 298.116
7.8u = 350 - 298.116
7.8u = 51.884
u = 51.884/7.8
u = 6.65m/s
Hence the rock's horizontal velocity was 6.65m/s
Answer:
C. were formed from plants which did not have time to decay
Explanation:
Coal beds are formed from plants which did not have time to decay. They usually form in an anoxic environment where oxygen is lacking and there is abundant plant matter.
The best place where coal beds can form is in a swamp.
Rapid burial of the plant matter without reacting with oxygen maintains the carbon content and the chemical energy they hound.
