Question

5. A certain force exerted for 0.5 s raises the speed of an object from 2.4 m/s to 4.9 m/s. Later, this same
force is applied for 2.5 s. How much does the speed of the object change in 2.5 seconds?
(Ans. 12.5 m/s​

Answer 1

Answer:Let the mass of the given object is m kg.

we know,

force × time = change in linear momentum.

i.e., F × t = m(v - u)

case 1 : A force, F exerted for 0.5 seconds raise the speed of the object from 2.4 m/s to 4.9 m/s.

so, F × 0.5s = m(4.9m/s - 2.4 m/s)

⇒F × 0.5 = m(2.5)

⇒F = 5m.....(1)

case 2 : same force exerted for 2.5 seconds. then, final speed becomes v.

so, F × 2.5 = m(v - 2.4)

from equations (1),

⇒5m × 2.5 = n(v - 2.4)

⇒12.5 = v - 2.4

⇒v = 14.9 m/s

hence, the speed of the object changes from 2.4 m/s to 14.9 m/s

Step-by-step explanation: