What is the earliest point in the universe that we can observe? why can’t we see back further than this?

Figure 9 on page 362 shows various motions of balls. the curved path followed by the yellow ball in b in picture b is result of a) inertia b) centripetal motion c) gravity and horizontal velocity d) linear motion

If the force applied to an object remains constant, is more power needed for the object to move faster ? explain

Afrequency generator sends a 550 hz sound wave through both water and ice. what is the difference in wavelength between the wave produced in ice and the wave produced in water?