Here is a link that should help you out
http://instituteforenergyresearch.org/topics/encyclopedia/fossil-fuels/
Answer:
0.903 seconds
Explanation:
To find how many seconds the acorn fall, we can use the formula for distance travelled with constant acceleration:
D = Vo*t + a*t^2/2,
where D is the distance travelled, Vo is the inicial speed, t is the time and a is the acceleration.
In our problem:
Vo = 0,
a = g = 9.81 m/s2,
D = 4 meters.
So, we can solve the equation to find the time:
4 = 0*t +9.81*t^2/2
4.905*t^2 = 4
t^2 = 4/4.905 = 0.8155
t = 0.903 seconds
Buoyancy from water. Buoyancy is an upward force on an object immersed in a fluid (i.e., a liquid or a gas), enabling it to float or at least to appear lighter.
Answer:
7200 N/m
Explanation:
Metric unit conversion
100g = 0.1 kg
5 cm = 0.05 m
50 cm = 0.5 m
As the block is released from the spring and travelling to height h = 1.5m off the ground, the elastics energy is converted to work of friction force and the potential energy at 1.5 m off the ground
The work by friction force is the product of the force F = 15N itself and the distance s = 0.5 m
Let g = 10 m/s2. The change in potential energy can be calculated as the following:
Therefore, as elastic energy is converted to potential energy and work of friction:
The work to stretch a spring from its rest position is
(1/2) (spring constant) (distance of the stretch)²
E = 1/2 k x² .
You said it takes 1700 joules to stretch the spring 3 meters from its rest position, so we can write
1700 joules = 1/2 k (3m)²
1 joule = 1 newton-meter
1700 N-m = 1/2 k (3m)²
Multiply each side by 2: 3400 N-m = k · 9m²
Divide each side by 9m² k = 3400 N-m / 9m²
= (377 and 7/9) newton per meter
