The correct answer is <span>3)

.
</span>
In fact, the total energy of the rock when it <span>leaves the thrower's hand is the sum of the gravitational potential energy U and of the initial kinetic energy K:
</span>

<span>As the rock falls down, its height h from the ground decreases, eventually reaching zero just before hitting the ground. This means that U, the potential energy just before hitting the ground, is zero, and the total final energy is just kinetic energy:
</span>

<span>
But for the law of conservation of energy, the total final energy must be equal to the tinitial energy, so E is always the same. Therefore, the final kinetic energy must be
</span>

<span>
</span>
Answer:
.
Explanation:
By Newton's Second Law, the acceleration
of an object is proportional to the net force
on it. In particular, if the mass of the object is
, then
.
Rewrite this equation to obtain:
.
In this case, the assumption is that the
force is the only force that is acting on the object. Hence, the net force
on the object would also be
Make sure that all values are in their standard units. Forces should be in Newtons (same as
, and the acceleration of the object should be in meters-per-second-squared (
). Apply the equation
to find the mass of the object.
.
Explanation:
It is given that,
Length of the rod, l = 14 cm = 0.14 m
Charge on the rod, 
We need to find the magnitude and direction of the net electric field produced by the charged rod at a point 36.0 cm to the right of its center along the axis of the rod, z = 36 cm = 0.36 m
Electric field at the axis of the rod is given by :

Where
is the linear charge density of the rod,


E = -7493170.57 N/C
or

Negative sign shows that the electric field is acting in inwards direction. Hence, this is the required solution.
Answer:
It is a measure of the electric force per unit charge on a test charge.
Explanation:
The magnitude of the electric field is defined as the force per charge on the test charge.
Since we define electric field as the force per charge, it will have the units of force divided by the unit of charge. This implies that the SI unit of electric field is given as Newton/Coulomb (N/C).
To solve this problem it is necessary to apply the concepts related to energy conservation.
In this case the kinetic energy is given as

Where,
m = mass
v= Velocity
In the case of heat lost energy (for all 4 wheels) we have to

m = mass
Specific Heat
= Change at temperature
For conservation we have to





Therefore the temperature rises in each of the four brake drums around to 47°C