B. It reflects a lot of light, transmits almost no light, and absorbs some light.
Answer:
The planets spun in epicycles.
Explanation:
The planets were not simply attached to a mystical sphere (“deferent”) but they were actually attached to a mini-sphere (“epicycle”) which rotated on the larger one.
Answer:
The system's potential energy is -147 J.
Explanation:
Given that,
Energy = 147 J
We know that,
System is isolated and it is free from external forces.
So, the work done by the external forces on the system should be equal to zero.
We need to calculate the system's potential energy
Using thermodynamics first equation
Put the value into the formula
Hence, The system's potential energy is -147 J.
Answer:
Option 5. 1 and 3
Solution:
The only forces acting on the tennis ball after it has left contact with the racquet and the instant before it touches the ground are the force of gravity in the downward direction and the force by the air exerted on the ball.
The ball after it left follows the path of trajectory and as it moves forward in the horizontal direction the force of the air acts on it.
In the whole projectile motion of the ball, the acceleration due to gravity acts on the ball thus the force of gravity acts on the ball in the downward direction before it hits the ground.
Answer:
Efficiency of a machine is how well the machine works and what the machine is capable of doing.
Mechanical advantage=Load/Effort.
720/180=4
