Explanation:
a) How much work is done by gravity?
- w = f x d
- w = 950 x 10 x 5.5 = 52250j
b) How much work is done by tension?
- v²=u²+2as
- 0.75²=0.25²+2a x5.5
- 0.56=0.06+2a x5.5
- 2a x5.5 = 0.56 - 0.06
- 2a x 5.5 =0.5
- 11a=0.5
- a = 0.5/11 = 0.05m/s²
w = f x d
w = 950 x 0.05 x 5.5 = 261.25j
Answer:
1960 J
Explanation:
Potential energy is given as the product of mass, height and acceleration due to gravity and expressed as mgh where m represent the mass of the swimmer, g is acceleration due to gravity and h is the height. Since the swimmer has just gone 4 m from the surface, that is the height that potential energy is converted to kinetic energy. This follows the law of transformation of energy since the energy can't be lost but rather transformed from one state to another. Therefore, substituting 50 kg for m, 4 m for h and 9.8 for g we obtain that PE=50*4*9.8=1960 J. Since it's not among the options here, maybe it is option D
Upper mantle
The theory of the plate tectonics uses the convection cells in the upper mantle layer as the foundation for the movement of the continents.
To put it simple the process is explained like the convection cells create a lot of pressure, that pressure, supported by the high temperatures and magma, influence the crust above, and manage to crack it on certain places. As the crust cracks, it becomes a separate entity, and under the enormous force from bellow it slowly moves into a particular direction, and that is actually the movement of the tectonic plates.
