Question

The velocity of a bullet changes from v₀ to v after the bullet has passed through a distance h in the plank. Assuming resistance offered is proportional to v², find the time of motion in the plank.

• A.
• B. t =
• C. t =
• D. t =

Answer 1

Answer: (C)

t =

Answer 2

F = -kv², a = $\frac { \mathrm { dv } } { \mathrm { dx } } \cdot \frac { \mathrm { dx } } { \mathrm { dt } } = \frac { - \mathrm { k } } { \mathrm { m } } \mathrm { v } ^ { 2 }$

or $\int _ { v _ { 0 } } ^ { \mathrm { v } } \frac { \mathrm { dv } } { \mathrm { v } } = \int _ { 0 } ^ { \mathrm { h } } \frac { - \mathrm { kdx } } { \mathrm { m } }$ .

or log_e

form (1) and (2) t =