Final answer:
Various true/false questions about physics were addressed, clarifying concepts such as simple machine efficiency, motion graphs, force requirements in space, electric-field patterns, wave interaction, pulse waves, and electromagnetism.
Step-by-step explanation:
The provided statements each pertain to a different aspect of physics, addressing efficiency, motion graphs, force, electric fields, wave interference, pulse waves, and electromagnetic induction.
- The efficiency of a simple machine is always less than 100 percent due to friction - True.
- The position vs time graph of an object that is speeding up is not a straight line; it curves upwards - False.
- An external force is required to set a stationary object in motion in space, assuming no gravitational or atmospheric friction - True.
- The electric-field lines from a positive point charge indeed spread out radially and point outward - True.
- The amplitude of one wave is generally independent of another unless they intersect or overlap, leading to interference - typically False.
- A pebble dropped in water creates a ripple, which is a type of pulse wave - True.
- When a bar magnet drops through a copper tube, it induces an electric current in the tube due to the change in magnetic flux - True.
- An external force is a force that originates outside of the system of interest and influences it - True.