Question

An object is moving on a straight line according to the equation s=3t2

+4t+5, when s is

measured in meter and t in sec. Find instantaneous velocities at 2 and 3 seconds also find out

acceleration of a body​

Answer 1

Explanation:

s = 3t² + 4t + 5

instantaneous velocity = ds/dt = (3t² + 4t + 5)/dt

v = 2×3t + 4

v = 6t + 4

instantaneous velocity at 2 sec = 6(2) + 4

= 12 + 4 = 16 ms-¹

instantaneous velocity at 3 sec = 6(3) + 4

= 18 + 4 = 22ms-¹

acceleration = dv/dt = (6t + 4)/dt

a = 6 ms-²

acceleration is constant here, not dependent on time

so, acceleration at 2 and 3 sec is 6 ms-².