Question

A bullet is straight upward with a velocity of 100 m/s from the top of a building 100 m high. Find its maximum height above the ground
500 m
600 m
1000 m
300 m

Answer 1

Question

A bullet is straight upward with a velocity of $100\,\mathrm{m/s}$ from the top of a building $100\,\mathrm{m}$ high. Find its maximum height above the ground?

a) $500\,\mathrm{m}$

b) $600\,\mathrm{m}$

c) $1000\,\mathrm{m}$

d) $300\,\mathrm{m}$

Solution

$h_0 = 100\,\mathrm{m};\quad v_0 = 100\,\mathrm{m/s}$

$$OY: y = h_0 + v_0 t - \frac{g t^2}{2};$$ $$0 = v_0 - g t_m; \quad t_m = \frac{v_0}{g} = 10\,\mathrm{s};$$ $$h_{\max} = h_0 + v_0 t_m - \frac{g t_m^2}{2};$$ $$h_{\max} = 100 + 100 \cdot 10 - 10 \cdot 10^2 / 2 = 600\,\mathrm{m}$$

Answer: b) $h_{\max} = 600\,\mathrm{m}$

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