A truck running at $90\, km h ^{-1}$ is brought to rest over a distance of $25\, m$. Calculate the retardation and time for which brakes are applied.
A truck running at $90\, km h ^{-1}$ is brought to rest over a distance of $25\, m$. Calculate the retardation and time for which brakes are applied.
$u=90 km h ^{-1}=25 m s ^{-1} ; v=0 ; S =25 m ; a=?$
$t=?$
$(i)$ Applying $v^{2}-u^{2}=2 a S$
$(0)^{2}-(25)^{2}=2 \times a \times 25$
$\Rightarrow$ $a=-\frac{625}{50}=-12.5 m s ^{-2}$
Therefore, retardation $=-a=12.5 m s ^{-2}$
$(ii)$ Applying $v=u+a t$
$0=25-12.5 \times t$
$12.5 t=25 \quad$ or $\quad t=2 s$
Similar Questions
A motor bike running at $90 \,km h ^{-1}$, is slowed down to $54 \,km h^{-1}$ by the application of brakes, over a distance of $40\, m$. If the brakes are applied with the same force, calculate $(i)$ total time in which bike comes to rest $(ii)$ total distance travelled by bike.
A motor bike running at $90 \,km h ^{-1}$, is slowed down to $54 \,km h^{-1}$ by the application of brakes, over a distance of $40\, m$. If the brakes are applied with the same force, calculate $(i)$ total time in which bike comes to rest $(ii)$ total distance travelled by bike.
Using following data, draw time-displacement graph for a moving object :
Time $(s)$
$0$
$2$
$4$
$6$
$8$
$10$
$12$
$14$
$16$
Displacement $(m)$
$0$
$2$
$4$
$4$
$4$
$6$
$4$
$2$
$0$
Use this graph to find average velocity for first $4\,\sec $, for next $4\,\sec $ and for last $6\,\sec $.
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| Time $(s)$ | $0$ | $2$ | $4$ | $6$ | $8$ | $10$ | $12$ | $14$ | $16$ |
| Displacement $(m)$ | $0$ | $2$ | $4$ | $4$ | $4$ | $6$ | $4$ | $2$ | $0$ |
Use this graph to find average velocity for first $4\,\sec $, for next $4\,\sec $ and for last $6\,\sec $.
Can the distance travelled by a particle be zero when displacement is not zero ?
Can the distance travelled by a particle be zero when displacement is not zero ?
$(a)$ Differentiate between speed and velocity.
$(b)$ When is a body said to have uniform velocity ?
$(c)$ How can we describe the position of an object ? Illustrate with suitable example.
$(a)$ Differentiate between speed and velocity.
$(b)$ When is a body said to have uniform velocity ?
$(c)$ How can we describe the position of an object ? Illustrate with suitable example.
By giving an example, prove that rest and motion are relative terms.
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