Answer:
= 40J
Explanation:
The work and energy theorem says that:

where
is the work of the force,
the final kinetic energy and
the initial kinetic energy.
Addittionally, the work of the force is calculate as force multiply by distance and if the crate inittialy is at rest, the initial kinetic energy is zero, so:

where F is the force and d the distance. Then, replacing values, we get:


it means that the system gain 40J of kinetic energy.
Answer:
7327 kg or 7.3 tons
Explanation:
We have Newton formula for attraction force between 2 objects with mass and a distance between them:

where
is the gravitational constant on Earth.
is the masses of the 2 objects. and R = 2.6m is the distance between them.
is the attraction force.



or 7.3 tons
Complete Question
The complete question is is shown on the first uploaded
Answer:
The elastic potential energy at point B is
The kinetic energy at point D is 
Explanation:
Looking at the given point we can observe that mechanically energy(i.e potential and kinetic energy ) is conserved and it value is 
So at point B


KE at point B is 50J
So 
Now at point D

at point D is 25J
So 
Answer:
1.176 N
Explanation:
= mass of the bottle = 0.30 kg
= initial speed of the bottle = 2.8 m/s
= final speed of the bottle = 0 m/s
= stopping distance traveled = 1.0 m
= magnitude of frictional force acting on bottle
Using work-change in kinetic energy theorem
N
direction :
frictional force acts in opposite direction of motion.