Answer:
The center of mass for the object is
from the origin
Explanation:
From the question we are told that
The mass of the first object is 
The position of first object with respect to origin 
The mass of the second object is 
The position of second object with respect to origin 
The mass of the third object is 
The position of third object with respect to origin 
The mass of the fourth object is 
The position of fourth object with respect to origin 
Generally the center of mass of the object along the x-axis is zero because all the mass lie on the y axis
Generally the location of the center mass of the object is mathematically represented as

=>
=>
Answer: W = 294 J
Explanation: Solution:
Work is expressed as the product of force and the distance of the object.
W = Fd where F = mg
W= Fd
= mg d
= 15 kg ( 9.8 m/s²) ( 2m )
= 294 J
What are the answer choices, if there are any?
Newton's second law states that the resultant of the forces applied to an object is equal to the product between the object's mass and its acceleration:

where in our problem, m is the mass the (child+cart) and a is the acceleration of the system.
We are only concerned about what it happens on the horizontal axis, so there are two forces acting on the cart+child system: the force F of the man pushing it, and the frictional force

acting in the opposite direction. So Newton's second law can be rewritten as

or

since the frictional force is 15 N and we want to achieve an acceleration of

, we can substitute these values to find what is the force the man needs: