Question

time : 4 sec ,mass : 7000 kg, velocity : 36 km / hr. find the force applied to Stop the bus.​

Answer 1

Step-by-step explanation:

Velocity of bus = 36km/hr = 36×5/18 m/s = 10m/s

Change in momentum = 7000kg(0m/s - 10m/s) = -70000 kgm/s

Therefore, Force = Change in momentum per unit time

= 70000/4 = 17500N = 17.5 KN

Answer 2

$\begin{gathered} \\ \huge\mathfrak {\underline \purple{ \: \: \: \: \: \: \: \: given \mapsto \: \: \: \: \: \: \: \: }} \\ \\ \end{gathered}$

Mass of the bus, ( m ) ⟿ 7000 kg

Time taken by the bus to stop, ( t ) ⟿ 4 second

Time taken by the bus to stop, ( t ) ⟿ 4 secondInitial velocity of the bus, ( u ) ⟿ 36 km/ hr

ㅤㅤㅤㅤㅤㅤㅤㅤ⟿ $\large \: \sf{{\large{\cancel{36}}}\times \large\frac{ 10 \cancel0 \cancel0 \: \red m \: \: }{ \cancel{36} \cancel0 \cancel0 \: \red s \: \: }}$

ㅤㅤㅤㅤㅤㅤㅤㅤ⟿ 10 m/s

ㅤㅤㅤㅤㅤㅤㅤㅤ⟿ 10 m/sFinal velocity of the bus ⟿ 0

ㅤㅤㅤㅤ( Because it comes to rest )

Acceleration of the bus ⟿ $\large \sf\frac{F}{m}$

$\begin{gathered} \\ \\ \end{gathered}$

$\begin{gathered} \\ \huge\mathfrak {\underline \purple{ \: \: \: \: \: \: \: \: \: formula \mapsto \: \: \: \: \: \: \: \: }} \\ \\ \\ \\ \large \bigstar \sf \boxed{ \bf \red {v = u + at}} \bigstar \\ \end{gathered}$

$\begin{gathered}\\ \huge\mathfrak {\underline \purple{ \: \: \: \: \: \: \: \: Solution \mapsto \: \: \: \: \: \: \: \: }} \\ \\ \end{gathered}$

Putting the Values ➲

$\begin{gathered} \large \sf \longmapsto 0 = 10 + (\frac{f}{m}) \times 4 \\ \\ \large \sf \longmapsto 0 = 10 + ( \frac{F}{7000}) \times 4 \\ \\ \large \sf \longmapsto 0 = 10 + \frac{4F}{7000} \\ \\ \large \sf \longmapsto 0 = \frac{70000 + 4F}{7000} \\ \\ \large \sf \longmapsto 0 = 70000 + 4F \\ \\ \large \sf \longmapsto - 70000 = 4 \: F \\ \\ \large \sf \longmapsto \: F = \frac{ - 70000}{4} \\ \\ \large \sf \longmapsto \boxed{ F= - 17500 \: \red N} \\ \\ \end{gathered}$

Therefore ,

the force applied to stop the bus = -17500 N

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