Calculate the potential energy of a 50 kg body at a height of 1.5 m, and its kinetic energy if it moves at 40 m/s.

The mass of the body is $m = 50\, \text{kg}$.
The height above the ground is $h = 1.5\, \text{m}$.
The acceleration due to gravity is $g = 9.8\, \text{m/s}^2$ (standard value).
The formula for potential energy ($PE$) is:

$$PE = mgh$$

$$PE = (50\, \text{kg})(9.8\, \text{m/s}^2)(1.5\, \text{m})$$ $$PE = 735\, \text{J}$$

The potential energy is $\boxed{\text{735 J}}$.

2. Calculate its kinetic energy.

The mass of the object is $m = 500\, \text{kg}$.
The velocity of the object is $v = 40\, \text{m/s}$.
The formula for kinetic energy ($KE$) is:

$$KE = \frac{1}{2}mv^2$$

$$KE = \frac{1}{2}(500\, \text{kg})(40\, \text{m/s})^2$$ $$KE = \frac{1}{2}(500\, \text{kg})(1600\, \text{m}^2/\text{s}^2)$$ $$KE = 250\, \text{kg} \times 1600\, \text{m}^2/\text{s}^2$$ $$KE = 400000\, \text{J}$$

The kinetic energy is $\boxed{\text{400,000 J}}$.