Question

a body starting from rest covers a distance of 0.45 kilometre and acquires a velocity of 300 kilometre per hour . Its acceleration will be? ​

Answer 1

G I V E N :

• Initial Velocity (u) = 0 m/s
• Distance travelled (s) = 0.45 km
• Final Velocity (v) = 300 km/hr

T O F I N D :

• Acceleration (a) = ?

S O L U T I O N :

First of all convert distance from km to m :

➵ Distance travelled (s) = 0.45 km

➵ Distance travelled (s) = 450 m

Now, convert Final Velocity from km/hr to m/s :

➺ Final Velocity (v) = 300 km/hr

➺ Final Velocity (v) = 300 × 5/18

➺ Final Velocity (v) = 250/3 m/s

Now, let's calculate the acceleration of body by using third equation of motion :

→ v² - u² = 2as

→ (250/3)² - (0)² = 2(a)(450)

→ 62500/9 = 900a

→ 62500 = 9 × 900a

→ 62500 = 8100a

→ a = 62500 ÷ 8100

→ a = 625 ÷ 81

→ a = 7.71 m/s²

Therefore, acceleration of the body is 7.71 m/s².

Answer 2

Given :

Initial Velocity of the body, u = 0 m/s.

Distance travelled, s = 0.45 km = 450m.

Final Velocity of the body, v= 300 km/hr.

To find :

Acceleration of the body

Solution :

First of all we have to convert km/hr to m/s

1km/hr = 5/18 m/s

300 km/hr = 300 × 5/18 = 250/3 m/s

As we are provided with initial Velocity, final velocity and distance covered we can use 3rd equation of motion .i.e.,

➠ v² - u² = 2as

➠ (250/3)² - (0)² = 2(a)(450)

➠ 62500/9 = 900a

➠ 62500 = 9(900a)

➠ 62500 = 8100a

➠ a = 62500/8100

➠ a = 7.71 m/s²${.}$

thus,acceleration of the body is 7.71m/s²

Remember !

SI unit of accerlation is metre per second (m/s).