I could be wrong on this one, but I think the answer is the first option,
The net force on the object is in the direction of motion.
Friction can be acting on the object, but if the other force(s) that are acting on the object are greater, I think the object will still be able to accelerate.
The third option can't be true, according to Newton's second law

. If there were no forces acting on the object, or if the net forces cancelled each other out, the object wouldn't be accelerating unless its mass was changing.
I suppose the last option is also technically true, but the first is more specific..?
Answer:
X-rays are most often used to examine bones and teeth.
Hope this helps!
Answer:
work being done on an object.
Answer. A. A man pushes a couch across the room
diagram identifies an axle:
Answer: B. Z
simple machine described as a shaft at the center of a wheel:
Answer: D. Wheel and axle
Type of lever:
A. a catapult
Answer:

Explanation:
= Permittivity of free space = 
A = Area
h = Altitude = 600 m
Electric flux through the top would be
(negative as the electric field is going into the volume)
At the bottom

Total flux through the volume

Electric flux is given by

Charge per volume is given by

The volume charge density is 
Answer:
754.3 m
Explanation:
The moment of inertia of the solid disk:

Where m is the disk mass and R is the radius of the disk.

The angular kinetic energy of the disk is then:

By law of energy conservation, this energy is converted to potential energy to pick up the 3kg block
let g = 9.8 m/s2

where
= 3 kg is the mass of block

