Answer:
2.019 seconds.
Explanation:
Here we use the equation:
Distance covered = (initial speed x time) + 0.5 x (acceleration x time^2)
The vertical distance to cover is 20 meters.
Since the cannonball is fired horizontally, the initial vertical speed is 0 m/s.
Acceleration due to gravity is 9.81 m/s^2.
Substituting these values into the equation we get:
20 = (0 x time) + 0.5 x (9.81 x time^2)
Solving this equation for time gives us 2.019 seconds as the answer.
Electrostatic forces between charges depend on the product of
the sizes of the charges, and the distance between them.
We should also mention the item about whether the charges are
both the same sign or opposite signs. That determines whether
the forces will pull them together or push them apart, which is a
pretty significant item.
Answer:
Upward: Negative
Downward: Positve
Explanation:
Let upward be positive
We want to find the work done on the object upwards.
The equation of work done due to gravity is
It is read as force of gravity times displacement times cos of the angle between the force and displacement.
Since gravity is happening down of the center of mass and the displacement is upwards, the angle is 180° so
Cosine of 180 is -1
so
If we go downwards, the sign will be positive because cos(0)=1