The contact force is indeed caused by "Contact".
Air resistance is basically a type of friction, which is apparently present providing two object contact.
The rest selections are all interaction force, which is not necessarily caused by contact.
The answer is d.... Knife.
Hope this helped :)
Answer with Explanation:
We are given that
Constant speed of Jane=12.6 m/s
a.When Fred can throw the ball 30 m/s
We have to find the angle relative to the horizontal when he throw the ball in order for Sue to see the ball travel vertically upward.
Let 
be the angle .
Therefore,
b.We have to find the height to which ball reach.
It is powered by the Earth's rotation and the moon gives a little boost.
Answer:
Friction, normal force, and weight
Explanation:
If the book slows down, it means that there must be friction acting in the opposite direction of the direction the book is moving in.
Weight is caused by the gravitational pull of the Earth on the book, and normal force is the table pushing the book up because the book is pushing down on the table (3rd law.)
Note that weight and normal force is not the 3rd law action-reaction pair. The pair is the force of the book on the table and the force of the table on the book.
