Question

time : 4 sec ,mass : 7000 kg, velocity : 36 km / hr. find the force applied to Stop the bus.( answer is - 17500N ) I will follow you if you can answer this questions ❤️❤️​

Answer 1

Given :

• Mass of the bus = 7000 kg
• Time = 4 sec
• Velocity of the bus = 36 km/hr

To Find :

• The Force applied to stop the bus

Solution :

using first equation of motion , v = u + at

Here ,

• v is final velocity
• u is initial velocity
• a is acceleration
• t is time

We have ,

• v = 0 {since it comes to rest}

• u = 36 km/hr = 36(5/18) m/s = 10 m/s

• t = 4 sec

• Mass = 7000 kg

Substituting the values ;

➙ 0 = 10 + (F/m)(4) { ∵ a = F/m}

➙ 0 = 10 + (F/7000)(4)

➙ 0 = 10 + (4F/7000)

➙ 0 = (70000 + 4F)/7000

➙ 0 = 70000 + 4F

➙ -70000 = 4F

➙ F = -70000/4

➙ F = -17500 N

Hence ,

• The Force that should be applied to bring the bus to rest is -17,500 N

Answer 2

$\\ \huge\mathfrak {\underline \purple{ \: \: \: \: \: \: \: \: given \mapsto \: \: \: \: \: \: \: \: }}$

• Mass of the bus, ( m ) ⟿ 7000 kg

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

• Initial 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

• Final velocity of the bus ⟿ 0

ㅤㅤㅤㅤ( Because it comes to rest )

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

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

$\\ \huge\mathfrak {\underline \purple{ \: \: \: \: \: \: \: \: Solution \mapsto \: \: \: \: \: \: \: \: }}$

Putting the Values ➲

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

Therefore , the force applied to stop the bus = -17500 N