Difference between 1st equation of motion and 2nd equation of motion
1st equation of motion
1.) The first equation of motion gives the relation between the initial velocity, final velocity, acceleration and time.
2.) Using graphical method, 1st equation of motion is derived as,
∴ v = u + at
Where, u = initial velocity
v =final velocity
a = acceleration
t = time.
3.) This equation can be used to find initial velocity, final velocity, acceleration or time using the given data.
4.) Eg. What will the acceleration of car if its speed changes from 36 km/h to 72 km/hr in 10 sec?
Here we have,
2nd equation of motion
1.) Second equation of motion gives the relation between initial velocity, displacement and acceleration of object.
2.) Using graphical method, 2nd equation of motion is derived as,
∴ s = ut + 1/2 at2
Where, u = initial velocity
s = displacement
a = acceleration
t = time.
3.) Second equation is very useful in finding the displacement, acceleration, initial velocity and time.
4.) Eg. Batsman hits the ball towards boundary at speed of 30 m/s and uniform acceleration of 1.2 m/s2 takes 1.6 seconds cross the boundary rope. What is the distance of boundary from the batting crease?
Ans: u=30 m/s, t= 1.6 sec, a = 1.2 m/s2
Using second equation of motion, we have
∴ s = ut + 1/2 at2
∴ s = 20 × 2 + ½ × 1.2 × 1.62
∴ s = 60 + 0.6 × 2.56 = 92.16 m