Question

Suppose two children push horizontally, but in exactly opposite directions, on a third child in a wagon. The first child exerts a force of 75.0 N, the second a force of 96.0 N, friction is 12.0 N, and the mass of the third child plus wagon is 27.0 kg.
(a) What is the system of interest if the acceleration of the child in the wagon is to be calculated? (Select all that apply.)
the wagon
the child in the wagon
the children outside the wagon


(b) Draw a free body diagram, including the weight and all other forces acting on the system. (Do this on paper. Your instructor may ask you to turn in this diagram.)
(c) Calculate the acceleration.
m/s2
(d) What would the acceleration be if friction is 21.0 N?

Answer 1

(a) The system of interest if the acceleration of the child in the wagon is to be calculated are the wagon and the children outside the wagon.

(b) The acceleration of the child-wagon system is 0.33 m/s².

(c) Acceleration of the child-wagon system is zero when the frictional force is 21 N.

Net force on the third child

Apply Newton's second law of motion;

∑F = ma

where;

• ∑F is net force
• m is mass of the third child
• a is acceleration of the third child

∑F = 96 N - 75 N - 12 N = 9 N

Thus, the system of interest if the acceleration of the child in the wagon is to be calculated are;

• the wagon
• the children outside the wagon

Free body diagram

           →                 →              Ф                         ←

         1st child      friction       wagon                2nd child

Acceleration of the  child and wagon system

a = ∑F/m

a = 9 N / 27 kg

a = 0.33 m/s²

When the frictional force is 21 N

∑F = 96 N - 75 N - 21 N = 0 N

a = ∑F/m

a = 0/27 kg

a = 0 m/s²

Learn more about net force here: brainly.com/question/14361879

#SPJ1