Answer:
The world wars. Most notably world War II
Explanation:
The demand for aircrafts during these events led to extensive research into the design of aircrafts. Aircraft advanced within these years from a simple design to a more complex design; capable of carrying fire power and even became bomb equipped. Also, the material of choice of production moved from wood to metal and the engine was improved on to gain more speed and maneuverability.
Answer:
a.
Here independent variable is negative reinforcement like punishment. The dependent variable is aggressiveness.
Control group : Teacher
Experiment group : Students
b.
Independent variable : Exercise
Dependent variable : Depression
Various levels of independent variables : The time of exercise may be increased or reduced
c.
Independent variable: Environment friendly messages
Dependent variables : Environment friendly behavior
Interaction: The verbal exchange among the peers.
