Pushing a large box to the left at 15N and pushing the same box to the left at 25N.

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What is the weight of a 8-kg substance in n, kn, kg·m/s2, kgf, lbm·ft/s2, and lbf?

The force it would take to accelerate an 900-kg car at the rate of 6m/s2

Would it be correct to say the doppler effect is the apparent change in the speed of a wave due to the motion of the source? be sure to fully explain your position using at least 3 complete content related sentences.