A car slows from 20 m/s to 5 m/s in 3 s. What is its acceleration?
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Acceleration is change in velocity divided by time.
(5-20)/3 = -5 m/s².
Practice NET Physics questions with answers and explanations.
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Acceleration is change in velocity divided by time.
(5-20)/3 = -5 m/s².
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Use s=ut+½at² with u=0.
S=½×2×25 = 25 m.
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Use s=ut+½at².
S=10×5+½×2×25 = 50+25 = 75 m.
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Use v²=u²+2as.
100-16 = 42a, so a=2 m/s².
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Starting from rest, v=gt.
V=10×2 = 20 m/s.
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Use s=½gt².
S=½×10×9 = 45 m.
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At maximum height, final vertical velocity is zero.
0=20-10t gives t=2 s.
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Use v²=u²-2gh with v=0.
0=400-20h, so h=20 m.
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Newton's second law gives F=ma.
F=5×4 = 20 N.
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The runner returns to the starting point, so displacement is zero.
Average velocity is therefore zero.
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Use v=u+at with u=0.
V=0+3×4 = 12 m/s.
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Use v=u+at.
V=5+2×6 = 17 m/s.