Answer:
0.045 J
Explanation:
From the question,
The elastic potential energy stored in a spring is given as,
E = 1/2ke²...................... Equation 1
Where E = elastic potential energy, k = spring constant, e = compression.
Given: k = 100 N/m, e = 0.05-0.02 = 0.03 m
Substitute these values into equation 1
E = 1/2(100)(0.03²)
E = 50(9×10⁻⁴)
E = 0.045 J
Hence the right option is 0.045 J
I would expect it to be slightly basic.
The answer is <span>It protects the seed until it matures.
Through the process of elimination:
- </span><span>It protects the seed until it matures. YES. A female pine cone the unfertilized seeds until they become mature. Then, the cone opens and seeds fall out of the cone.
</span><span>- It makes food for the adult plant. NO. The food of plants in made of green leaves that contain chlorophyll in the process of photosynthesis.
- It allows for photosynthesis to occur. NO. The cones have nothing to do with photosynthesis but they are responsible for reproduction.
- It acts as an object to attract birds. NO. The birds look for colourful flowers while cones are woody.
- It serves as an ornamental object on the tree. NO. Every part of plants has more important function than serving as an ornamental object.</span><span>
</span>
Energy to lift something =
(mass of the object) x (gravity) x (height of the lift).
BUT ...
This simple formula only works if you use the right units.
Mass . . . kilograms
Gravity . . . meters/second²
Height . . . meters
For this question . . .
Mass = 55 megagram = 5.5 x 10⁷ grams = 5.5 x 10⁴ kilograms
Gravity (on Earth) = 9.8 m/second²
Height = 500 cm = 5.0 meters
So we have ...
Energy = (5.5 x 10⁴ kilogram) x (9.8 m/s²) x (5 m)
= 2,696,925 joules .
That's quite a large amount of energy ... equivalent to
straining at the rate of 1 horsepower for almost exactly an
hour, or burning a 100 watt light bulb for about 7-1/2 hours.
The reason is the large mass that's being lifted.
On Earth, that much mass weighs about 61 tons.
