Question

a car travelling at a speed of 54km/h is bought to rest in 90 seconds find the acceleration and distance travelled by car before coming to rest

Answer 1

Answer on Question #43188, Physics, Mechanics | Kinematics | Dynamics

A car travelling at a speed of $54\mathrm{km/h}$ is bought to rest in 90 seconds and distance travelled by car before coming to rest

Solution.

From definition of acceleration we obtain:

$$a = \frac {\Delta V}{\Delta t}$$ $$\Delta V = 5 4 \frac {k m}{h} = 1 5 \frac {m}{s}; \Delta t = 9 0 s$$

Thus:

$$a = \frac {1 5 \frac {m}{s}}{9 0 s} \approx 0. 1 6 7 \frac {m}{s ^ {2}}$$

Travelled distance:

$$L = \frac {a \Delta t ^ {2}}{2} = \frac {\Delta V \Delta t}{2} = \frac {1 5 \frac {m}{s} \cdot 9 0 s}{2} = 6 7 5 m$$

Answer:

$$a \approx 0. 1 6 7 \frac {m}{s ^ {2}}$$ $$L = 6 7 5 m$$

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