An electromagnetic launcher sled is decelerating on a straight, horizontal test track. The sled is initially cruising at a constant speed of 40 m s−140\text{ m s}^{-1}40 m s−1. When an emergency stop command is initiated, there is a system telemetry delay of 0.25 s0.25\text{ s}0.25 s before the mechanical friction brakes engage. The total stopping distance of the sled, measured from the exact instant the stop command is initiated, is 110 m110\text{ m}110 m.
Calculate the magnitude of the constant deceleration of the sled while the friction brakes are active.
A physics researcher slides a polymer puck of mass MMM across a high-friction synthetic sheet to investigate the constant resistive force FFF opposing its motion.
The researcher wishes to investigate how the total sliding distance xxx before the puck comes to rest depends on its initial projection speed vvv.
The initial speed vvv and distance xxx are related by the work-energy equation:
12Mv2=Fx \frac{1}{2}Mv^2 = Fx 21Mv2=Fx10 exam-style questions on OCR A A Level Physics Forces in action, covering Dynamics, Motion with non-uniform acceleration, Equilibrium, and Density and pressure. Each one has a worked solution and a mark scheme showing where the marks go.