Answer to Question #175017 in Classical Mechanics for Mary Chumanni

Question

An antelopes moving with constant acceleration covers the distance between two points 70.0m apart in 7.0s. It’s speed aa it passes the second point is 15.0m/s

A.) What is it’s speed at the first point? b) What is the acceleration?

Answer 1

(a)

$$d=\dfrac{1}{2}(v_i+v_f)t,$$ $$v_i=\dfrac{2d}{t}-v_f,$$ $$v_i=\dfrac{2\cdot70\ m}{7\ s}-15\ \dfrac{m}{s}=5\ \dfrac{m}{s}.$$

(b)

$$v_f=v_i+at,$$ $$a=\dfrac{v_f-v_i}{t}=\dfrac{15\ \dfrac{m}{s}-5\ \dfrac{m}{s}}{7\ s}=1.43\ \dfrac{m}{s^2}.$$