Answer:
Paul B. MacCready, 81; inventor of human-powered aircraft, other innovations. Paul B. MacCready, the Caltech-trained scientist and inventor who created the Gossamer Condor -- the first successful human-powered airplane -- as well as other innovative aircraft, has died. He was 81.
Explanation:
The force acting on the boulder bringing it down the mountain? Would be gravity. Not sure about any of the multiple choice options you have
Answer:

Explanation:
given,
torque = 47 N m
length of wrench = 25 cm = 0.25 m
angle with respective = 115°
The torque on the wrench





The required force is equal to 
Answer:
In order to move forward, Letti needs to be creative.
Explanation:
Creative:
A person is said to be creative if that person has ability to think out of the box.
For example: if a person having a problem and instead of using traditional methods of solving the problem then that person thinks about news ideas then that person is creative,
As in our case, letti can use problem solving technique to find a solution of her problem.
Creative Problem technique:
It is such a problem solving method in which we use unconventional ways to get the solution of a problem. We analyze the problems with news view points so that we can reach at innovative ideas of solutions.