Final answer:
The statements regarding average speed and velocity, normal force, the requirement of an external force in space, the direction of body movement under unequal forces, the comparison of kinetic and static friction, and the changes in kinetic and potential energy of a rock thrown in the air have been addressed as either true or false with explanations.
Step-by-step explanation:
Understanding Forces and Motion
True or False: The average speed of the ball will be less than the average velocity of the ball. The answer is b. False. Average speed is the total distance traveled divided by the total time taken, whereas average velocity is total displacement divided by total time. In straight-line motion, they can be the same, but in other scenarios, average speed can be greater due to the path taken.
True or False: Normal reaction is the force that opposes the force of gravity and acts in the direction of the force of gravity. This is b. False. The normal force acts perpendicular to the surface, not in the direction of gravity.
True or False: An external force is required to set a stationary object in motion in outer space away from all gravitational influences and atmospheric friction. This is a. True. According to Newton's First Law, an external force is required to change the state of motion of an object.
True or False: When two unequal forces act on a body, the body will not move in the direction of the weaker force. This is a. True. The body will move in the direction of the resultant force, which is in the direction of the stronger force.
True or False: Kinetic friction is less than the limiting static friction because once an object is moving, there are fewer points of contact, and the friction is reduced. This statement is a. True. It is generally harder to start moving an object than to keep it moving due to static friction being higher than kinetic friction.
True or False: If a rock is thrown into the air, the increase in the height would increase the rock's kinetic energy, and then the increase in the velocity as it falls to the ground would increase its potential energy. This statement is b. False. When a rock is thrown upward, its potential energy increases with height, while kinetic energy decreases and vice versa on the way down.