Question

Check my answers please?

1. Which of these situations involves dynamics rather than kinematics?
(Points : 1)
using a velocity vs. time graph to find the distance traveled
-->studying the net forces on objects
finding the time of travel from the velocity
finding the acceleration from a velocity-time graph

2. A student has just started pulling hard enough for a crate to start accelerating into motion. At that particular instant, what is the net force on the crate if the force of friction has magnitude 200 N and the applied force is 225 N?
(Points : 1)

Answer 1

-->25 N in the direction the student is pulling
25 N opposite to the direction the student is pulling
0 N
425 N in the direction the student is pulling

3. Which of these is not one of the four fundamental forces of nature?
(Points : 1)
strong nuclear force
weak nuclear force
gravity
-->friction

4. Each of the answers below involves some kind of force. Of these, which is an example of a force acting through a distance?
(Points : 1)
-->meteor falling to the earth
long rope holding an object off the ground
winch pulling a car out of a ditch
golf ball flying through the air after being hit by a golf club

5. Which of these forces is most similar to electrical forces?
(Points : 1)
weight of an object
-->force between two magnets
force that holds the parts of atomic nuclei together
force attracting the moon to the earth

6. Suppose you are seated motionless in a chair. What is the net force acting on you?
(Points : 1)
your weight
force that the chair exerts upward
force you exert on the chair
-->zero

7. Suppose you are on a team in a tug-of-war. You are pushing your feet into the ground, and the ground is pushing back on you. The rope is also pulling you. The result of all your effort is that you are holding your position and not moving. What is the net force acting on you?
(Points : 1)
equal to the force from the rope
equal to the force from the ground
equal to the force of gravity
-->zero

Answer 2

I think you have them all correct.