Question

a car is moving with a speed of 20m/s, after applying the break it has come to rest after 10 seconds. what is its acceleration​

Answer 1

Answer:

- 2 m/s²

Explanation:

As per the provided information in the given question, we have :

• Initial velocity (u) = 20 m/s
• Final velocity (v) = 0 m/s [Comes to rest]
• Time taken (t) = 10 seconds

We've been asked to calculate the acceleration.

»› Acceleration is the rate of change in velocity with time. It is a vector quantity that means it has both magnitude and direction. And, its SI unit is m/s².

As acceleration is the rate of change in velocity, so:

⇒ Acceleration = Change in velocity/Time

⇒ Acceleration = ∆v/t

⇒ a = (v - u)/t

⇒ a = (0 - 20)/10

⇒ a = -20/10 m/s²

⇒ a = -2 m/s²

∴ The acceleration is -2 m/s². Negative sign indicates that the speed is decreasing.

⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀

Points to remember :

• We can also find the acceleration using the first equation of motion if we are provided with v, u , t .
• First Equation Of Motion : v = u + at
• Second Equation Of Motion : s = ut + ½at²
• Third Equation Of Motion : v² - u² = 2as

Answer 2

$\huge\purple{ \underline{ \boxed{\mathbb{\red{QUESTION : }}}}}$

A car is moving with a speed of 20 m/s , after applying the break it has come to rest after 10 seconds . What is its acceleration ?

$\huge\purple{ \underline{ \boxed{\mathbb{\red{ANSWER : }}}}}$

• $\textsf{Acceleration = \sf - 2 \: m {s}^{ - 2} }$

$\huge\purple{ \underline{ \boxed{\mathbb{\red{EXPLANATION : }}}}}$

$\green{ \large \underline{ \mathbb{\underline{GIVEN : }}}}$

• Initial Velocity ( u ) = 20 m/s

• Final Velocity ( v ) = 0 m/s ( At rest )

• Time taken ( t ) = 10 s

$\green{ \large \underline{ \mathbb{\underline{TO \: FIND : }}}}$

• Acceleration of car ( a ) .

$\green{ \large \underline{ \mathbb{\underline{ EQUATION \: OF \: MOTION \: USED : }}}}$

$\purple{ \boxed{ \sf \: v = u + at \: }}$

$\green{ \large \underline{ \mathbb{\underline{SOLUTION: }}}}$

$\displaystyle \sf \longrightarrow v = u + at \: \: \: \: \: \: \: \: \: \: \\ \\ \displaystyle \sf \longrightarrow 0 = 20 + a(10) \: \\ \\ \displaystyle \sf \longrightarrow 0 = 20 + 10a \: \: \: \: \\ \\ \displaystyle \sf \longrightarrow 20 + 10a = 0 \: \: \: \: \\ \\ \displaystyle \sf \longrightarrow 10a = - 20 \: \: \: \: \: \: \: \: \\ \\ \displaystyle \sf \longrightarrow a = \frac{ - 20}{10} \: \: \: \: \: \: \: \: \: \: \: \\ \\ \displaystyle \sf \longrightarrow a = - 2 \: m {s}^{ - 2} \: \: \:$

$\purple{ \boxed{ \textsf{Acceleration of car } \sf = - 2 \: m {s}^{ - 2} \: \: \: \: }}$

$\green{ \large \underline{ \mathbb{\underline{KNOW\:MORE: }}}}$

• Acceleration

Acceleration is the rate at which velocity changes with time . Acceleration can be negative , positive or zero . Negative acceleration is called retardation .

• Initial Velocity

Initial velocity is the velocity of the object before the effect of acceleration .

• Final Velocity

Final velocity is the velocity of the object after the effect of acceleration .

$\Large{\purple{\boxed{\begin{array}{l} \textsf{Equations of motion : } \\ \\ \textsf{v = u + at} \\ \\ \displaystyle\textsf{s = ut + \sf\frac{1}{2}a {t}^{2} } \\ \\ \sf {v}^{2} - {u}^{2} = 2as \end{array}}}}$