Answer:
Explanation:
Static friction occurs when an object initially starts at rest. When the surfaces of the materials touch, the microscopic unevenness interlock greatest with each other, causing the most friction out of the three.
During sliding friction, an object is already moving or in motion. The microscopic surfaces still interlock, but because the object is in motion, it has a momentum. Therefore, the magnitude of sliding friction is less than that of static friction.
Rolling friction occurs when an object rolls across some surface. Rather than surfaces interlocking, rolling friction is caused by the constant distortion of surfaces. As it rolls, the surfaces of the object are constantly wrapping and changing. This distortion causes the rolling friction. However, it is much less in magnitude when compared to static or sliding friction.
Gravity is a non contact force , jump from a little high place (don't do that :P) , you wont just get stuck in the air you will fall down , this is gravity you dont need any contact
Answer:
The magnitude of the free-fall acceleration at the orbit of the Moon is 
(
, where 
).
Explanation:
According to the Newton's Law of Gravitation, free fall acceleration (
), in meters per square second, is directly proportional to the mass of the Earth (
), in kilograms, and inversely proportional to the distance from the center of the Earth (
), in meters:
(1)
Where:
- Gravitational constant, in cubic meters per kilogram-square second.
- Mass of the Earth, in kilograms.
- Distance from the center of the Earth, in meters.
If we know that 
, 
and 
, then the free-fall acceleration at the orbit of the Moon is:
Answer:
1-In a uniform electric field, the field lines are straight, parallel, and uniformly spaced this statement is true.
2-Electric field lines near positive point charges radiate outward. this statement is also true.
3-The electric force acting on a point charge is proportional to the magnitude of the point charge. this statement is true as well.
Explanation:
the electric field created by a point charge is defined by E=KQ/r^2 where k is constant, q is magnitude of charge and r is the distance away from the point charge so the electric filed is distance dependent and can not be constant at all distances.
electric field lines near a negative point charge are directed radially inward because negative charge attracts the field and is not clockwise.
Mmm tricky.
Since the velocity is constant, I'm going to assume there is no acceleration in any direction. This means there is no net force in the I or J forection!
Since there are 2 forces, both must be equal and opposite in direction to perfectly cancel each other out.
So the opposite of F1 is (-2N)I + (6N)J!
