1) KE=1/2*m*v^2
1/2*45*40^2
KE=36,000J
2) PE=mgh
45*9.81*30
PE=13243.5J
Answer:
Yes, since the choice of the zero o potential energy is arbitrary.
Explanation:
The kinetic energy is due to the motion of the object. The expression for the kinetic energy is as follows;

Here, m is the mass of the object and v is the velocity of the object.
The kinetic energy can not be negative as the velocity is squared. It can be zero and positive.
Potential energy: It is the energy is due to the position of the object.
The expression for the potential energy is as follows;
PE= mgh
Here, g is the acceleration due to gravity and height.
Height can be taken from the reference point, zero which can be taken below zero and above zero. Zero is taken as origin. Below zero, the height is taken as negative and above zero, the height is taken as positive.
The potential energy can be zero, positive and negative.
The total energy is the sum of kinetic energy and potential energy.
E= KE + PE
Here, KE is the kinetic energy and PE is the potential energy.
Therefore, the option (B) is correct.
<u>We are given:</u>
Mass of Neptune = 1.03 * 10²⁶ kg
Distance from the center of Neptune (r) = 2.27 * 10⁷
now, computing the value of the acceleration due to gravity (g)
<u>Finding g:</u>
We know the formula:
g = G(mass of planet) / (r)²
g = [6.67 * 10⁻¹¹ * 1.03*10²⁶] / (2.27*10⁷) [since G is 6.67*10⁻¹¹]
g = (6.87 * 10¹⁵) / (5.15 * 10¹⁴)
which can be rewritten as:
g = (6.87 * 10¹⁵ * 10⁻¹⁴) / 5.15
g = (6.87 * 10¹⁵⁻¹⁴) / 5.15
g = (6.87/5.15) * 10
g = 1.34 * 10
g = 13.4 m/s² <em>(approx)</em>
The acceleration of the particle at time t is:

The velocity of the particle at time t is given by the integral of the acceleration a(t):

and the position of the particle at time t is given by the integral of the velocity v(t):

Assuming the particle starts from position x(0)=0 at t=0, the distance the particle covers in the first t=2 seconds can be found by substituting t=2 s in the equation of x(t):