Answer:
The speed of the cart at time 3.5 sec is 0.37 m/s.
Step-by-step explanation:
Given that,
Mass = 2.29 kg
Speed = 0.21 m/s
Force = at²
a = 0.0200 N/s²
Suppose we find the speed of the cart at 3.5 sec after the fun is turn on
We need to calculate the acceleration
Using newton's law


The speed of the cart at time 3.5 sec is
Using equation of motion
Put the value into the formula



Hence, The speed of the cart at time 3.5 sec is 0.37 m/s.