Answer:

Explanation:
The work done on a particle by external forces is defined as:

According to Newton's second law
. Thus:

Acceleration is defined as the derivative of the speed with respect to time:

Speed is defined as the derivative of the position with respect to time:

Kinetic energy is defined as
:

The force required to slow the truck was -5020 N
Explanation:
First of all, we find the acceleration of the truck, which is given by

where
v is the final velocity
u is the initial velocity
t is the time
For the truck in this problem,
v = 11.5 m/s
u = 21.9 m/s
t = 2.88 s
So the acceleration is

where the negative sign means that this is a deceleration.
Now we can find the force exerted on the truck, which is given by Newton's second law:

where
m = 1390 kg is the mass of the truck
is the acceleration
And substituting,

So the closest answer among the option is -5020 N.
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Answer:
1375J
Explanation:
The gravitational potential/potential energy of the at the top of the tree which is the energy by virtue of its position.
P.E = mgh
mass = m
Acceleration due to gravity = g
height = h
At the top of the tree, the value of h (height) is high resulting in the gravitational potential. When the cat lands on the ground, the value of h is zero, the the gravitational potential would be zero and all the potential energy have been converted to other forms of energy.
Therefore, the total gravitational potential store is equal to the maximum amount of energy that can be transferred which is equal to 1375J.