Answer:
This slide shows the three forces that act on a baseball in flight. The forces are the weight, drag, and lift. Lift and drag are actually two components of a single aerodynamic force acting on the ball. Drag acts in a direction opposite to the motion, and lift acts perpendicular to the motion
Answer:
Technically everything has somewhat of a magnetic field. I guess
We can use the equation for kinetic energy, K=1/2mv².
Your given variables are already in the correct units, so we can just plug in the variables and solve for v.
K = 1/2mv²
16 = 1/2(2)v²
16 = (1)v²
√16 = v
v = 4 m/s
Therefore, the velocity of a 2 kg mass with 16 J of kinetic energy is 4 m/s.
Hope this is helpful!
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: