Question

A particle has initial velocity $10$ m/s. It moves due to a constant force along the line of velocity which initially produces retardation of $5m/s^2$. Then the distance travelled in first $3$ seconds is?

• A. $10.0$m
• B. $7.5$m
• C. $2.5$m
• D. $17.5$m

Answer 1

The correct option is B $7.5$m

From newtons equation of motion $s=ut+\frac{1}{2}a{t}^{2}s=\left(10\right)\left(3\right)-\frac{1}{2}\left(5\right)\left(3^2\right)s=7.5m$

Acceleration is considered as negative as it is opposing the motion of the particle.