Question

a body moving with initial velocity of 10 ms, decelerates uniformly o come to rest in 40 m.find (a)it's deceleration,(b)it's time taken​

Answer 1

Given :

Initial velocity : 10 m/s

Final velocity : zero

Distance travelled : 40 m.

To find :

The deceleration and the time taken by the body.

Solution :

As we are provided with initial velocity, final velocity and distance travelled we can find accerlation using 3rd equation of motion that is

v² - u² = 2as

Where

• v denotes final velocity
• u denotes initial velocity
• a denotes acceleration
• s denotes distance

Now substituting all the given values in the formula,

➝ v² - u² = 2as

➝ (0)² - (10)² = 2a(40)

➝ -100 = 80a

➝ -100/80 = a

➝ a = -1.25 m/s²

Thus, acceleration of the object is -1.25m/s²

If the speed is decreasing with time then accerlation is negative. The negative accerlation is called deceleration or retardation.

Now using 1st equation of kinematics that is,

➝ v = u + at

➝ 0 = 10 + (-1.25)t

➝ -10 = -1.25t

➝ t = 10/1.25

➝ t = 8 sec

Thus, the time taken is 8 sec.

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Know more :

First equation of kinematics : v = u + at

Second equation of kinematics : s = ut + 1/2at²

Third equation of kinematics : v² - u² = 2as

Answer 2

Given:

Initial velocity: 10 m/s

Final velocity: zero(0)

Distance travelled : 40 m.

To find:

The deceleration and the time taken by the

body.

Solution :

As we are provided with initial velocity, final

velocity and distance travelled we can find

accerlation using 3rd equation of motion

that is

v²-u² = 2as

Where

• v denotes final velocity

• u denotes initial velocity

• a denotes acceleration

• s denotes distance

Now substituting all the given values in the

formula,

→v²-u² = 2as

→ (0)²-(10)² = 2a(40)

→-100 80a

→-100/80 = a

→ a=-1.25 m/s²

Thus, acceleration of the object is

Thus, acceleration of the object is-1.25m/s²

If the speed is decreasing with time then

accerlation is negative. The negative

accerlation is called deceleration or

retardation.

Now using 1st equation of kinematics that

is,

→v=u+at

→ 0= 10 + (-1.25)t

→-10-1.25t

→t 10/1.25

→ t = 8 sec

Thus, the time taken is 8 sec.

Know more:

First equation of kinematics : v= u + at

Second equation of kinematics : s = ut +

1/2at²

Third equation of kinematics : v² - u² = 2as