Mechanical Engineers study:

 Statics: How are forces transmitted to and throughout a structure?

Dynamics: What are the velocities,accelerations and resulting forces for a system in motion?

Kinematics: How does a mechanism behave as it moves through its range of motion?

Strength of Materials: Is the component strong enough to support the loads? Is it stiff enough?

Materials Science: Which material has the optimum properties?

Thermodynamics : How does energy get converted to useful power? What are the losses?

Fluid Mechanics: What is the pressure drop due to the fluid flow? What are the aerodynamic drag forces?

Heat Transfer: How do you calculate heat transfer rates from temperature data?  How do you predict the temperature distributions?

Manufacturing: What manufacturing processes do you select?

Machine Design: How do you synthesize all of the above?

Electrical Circuits: How do you integrate electronic controls into your design?

Laboratory Methods: How do you make and interpret both thermal and mechanical measurements?

Vibrations: How do you predict and control vibrations?

Engineering Economics: How do you estimate manufacturing costs?