Question

A boy is exerting a force of 70 N at a 50-degree angle on a law mower. He is accelerating at 1.8 m/s2. Round the answers to the nearest whole number. What is the mass of the lawn mower? Kg what is the normal force extered on the lawn mower? N

Answer 1

The mass of the lawn mower is 39 kg and the normal force exerted on the lawn mower is 246 N

Explanation:

According to second law of motion proposed by Newton, force applied on an object is directly proportional to the mass of the object and the acceleration acted by the object. So, from this law, we can determine the mass of the lawn mower.

Then the normal force applied on lawn mower is nothing but the perpendicular force acting upwards on it. So, to determine the lawn mower's mass, the steps are as follows:

Force exerted on the lawn mower = product of Mass and Acceleration of the lawn Mower

             $70=\text { Mass of the lawn mower } \times 1.8$

             $\text { Mass of the lawn mower }=\frac{70}{1.8}=39 \mathrm{kg}$

And then to determine the normal force,

$\text {Normal force }=\text {mass of the lawn mower } \times \text {acceleration due to gravity }\times\cos\theta$

Here, θ is the angle at which the boy is exerting force on the lawn mower. Also the acceleration is considered as acceleration due to gravity because the normal force is upward force acting against acceleration due to gravity.

So,

$\text { Normal force acting on the lawn mower }=39 \times 9.8 \times \cos 50$

             Normal force acting on the lawn mower = 246 N