Describe what an Astronomical Unit is and how you calculate it.
can someone plss help me??

20. threshold braking in the vehicle's braking system occurs when a. the brake pedal is pushed, heel on floorboard, with full foot pressure. b. the brakes are exerting full braking power, without traction loss. c. the driver begins pushing down the brake pedal, with moderate slowdown. d. the brakes just begin to take hold with a gradual slowdown.

Find v(t), given acceleration a(t)=7j and initial velocity v(0)=k

Because light travels in a straight line and casts a shadow, isaac newton hypothesized that light is