They don't have free electrons moving around (delocalised electrons) so they can't conduct electricity which gives them the property of good insulators.
Please see attached picture for answer an explanation.
1575 N
Explanation:
Step 1:
Let us consider that 350 J of energy is spent by that person to push a couch to 4.5 m from its initial position.
Let F be the force required and E be the energy spent and D be the distance traveled by the couch from its initial state.
In Physics, Work done = Force / Displaced distance
Step 2:
Let the work done be 350 J and Distance be 4.5 m
Then Force exerted = 
Relative time
seems to fit with this type of question.
Hope i Helped!
Which body is in equilibrium?
(1) a satellite orbiting Earth in a circular orbit
. No. The forces on it are unbalanced. There's only one force acting on it ... the force of gravity, pulling it toward the center of the Earth. That's a centripetal force, and the satellite is experiencing centripetal acceleration.
(2) a ball falling freely toward the surface of Earth. No. The forces on it are unbalanced. There's only one force acting on it ... the force of gravity, pulling it toward the center of the Earth. The ball is accelerating toward the ground.
<em>
(3) a car moving with a constant speed along a straight, level road. YES.</em> We don't even need to analyze the forces, just look at the car. It's moving in a straight line, and its speed is not changing. The car's acceleration is zero ! That right there tells us that the NET force ... the sum of all forces acting on the car ... is zero. THAT's called 'equilibrium'.
(4) a projectile at the highest point in its trajectory. No. The forces on it are unbalanced. There's only one force acting on it ... the force of gravity, pulling it toward the center of the Earth. The projectile is accelerating toward the ground.
