30 points
part one:
a crate is pulled by a force (parallel to the
incline) up a rough incline. the crate has an
initial speed shown in the figure below. the
crate is pulled a distance of 5.59 m on the
incline by a 150 n force.
the acceleration of gravity is 9.8 m/s^2
a) what is the change in kinetic energy of
the crate?
answer in units of j.

part two:
b.)what is the speed of the crate after it is
pulled the 5.59 m?
answer in units of m/s.

answer:

none of the above

explanation:

the actual answer is '91 protons'. in fact, the beta decay of the thorium-234 is the following:

where inside the nucleus of thorium (90 protons), a neutron turns into an electron (the beta particle) + a proton. therefore, the resulting nucleus (which is protoactinium) has a total of 90+1 = 91 protons.

so, the correct answer would be '91 protons'.

answer:

592 j

explanation:

when neglecting air resistance or frictions, the mechanical energy of an object in motion is conserved.

mechanical energy is defined as the sum of potential energy (u) and kinetic energy (k):

at the highest point of its swing, the pendulum has only potential energy (because its motion has stopped), therefore its mechanical energy at the highest point is:

on the contrary, at the lowest point of its swing, the pendulum has only kinetic energy, because it is a its lowest height, so the potential energy is zero, and all the mechanical energy is just kinetic energy:

and since for the conservation of energy e must be conserved, we have

so, the kinetic energy at the bottom of its swing is 592 j.