Question

The graph below shows the "x-direction" position of a charged particle flying around in space and accelerating due only to some electric field.
During which time interval is the force on the particle in the x-direction greatest?

• A. $5$ to $6$ seconds
• B. $6$ to $7$ seconds
• C. $7$ to $8$ seconds
• D. $8$ to $9$ seconds
• E. $10$ to $11$ seconds

Answer 1

The correct option is B $6$ to $7$ seconds

The force acting a particle is given by $F=ma=m\frac{dv}{dt}=m\frac{d^{2}x}{{dt}^2}$.

Hence the direction of force is the sign of the rate of change of slope of the curve.

For options A, C, D and E, the slope of the curves is constant.

For option B, from 6 to 7 seconds, the slope of curve is going from being negative to positive. Hence it is increasing positively, and hence the particle is accelerating.