Final answer:
The particle's speed 3 seconds after starting from rest, with an acceleration of 5.2 m/s², is 15.6 m/s, calculated using the kinematic equation for velocity.
Step-by-step explanation:
The subject of this question is Physics, and it is at a High School grade level. Given that a particle accelerates from rest with an acceleration of 5.2 m/s², we can use the kinematic equation for velocity to find its speed after 3 seconds. The equation is v = u + at, where v is the final velocity, u is the initial velocity, a is the acceleration, and t is the time.
Since the particle starts from rest, the initial velocity u is 0. Plugging in the values, we get:
• v = 0 + (5.2 m/s²)(3 s)
• v = 15.6 m/s
Therefore, the particle's speed 3 seconds after starting from rest is 15.6 m/s.