Question

An adult lion standing in Las Vegas has a mass of $210{\text{ kg}}$ . How much force is exerted downward on the lion by gravity (i.e., the weight)? How much Normal force pushes up the lion?

Answer 1

Hint : In order to find the answer to the above question, we have to use the below expression of force,
$F = m \times a$
Where, F is force, m is mass, a is acceleration.

Complete Step By Step Answer:
As asked in the question about the force on the lion by gravity, we have to use the acceleration here as acceleration due to gravity, hence the above equation will become,
${\text{F = m}} \times {\text{g}}$
Where, F is force on lion by gravity
m is mass of lion
g is acceleration due to gravity
As mass of the lion is given in question as $210{\text{ kg}}$ and we know that the acceleration due to gravity is $9.8{\text{ m/}}{{\text{s}}^2}$ . So after substituting these values in above equation we will get,
${\text{F = 210}} \times {\text{9}}{\text{.8}}$
${\text{F = 2058 N}}$
Now for Normal reaction on a lion, we all know that it will be equal to the force exerted by the lion on earth by the third law of motion which says for every action there is an equal and opposite reaction. As said opposite the direction of normal will be upward and hence should be taken as negative.
${\text{N = - 2058 N}}$ .

Note :
The direction of force as asked in the question was downward and so is the direction of force of attraction on everybody by earth hence we have taken direction of acceleration due to gravitation as positive.
One must pay keen attention to the direction and sign of the force.