Answer:
The distance travelled does not depend on the mass of the vehicle. Therefore, 
Explanation:
This deceleration situation can be analyzed by means of Work-Energy Theorem, where change in translational kinetic energy is equal to the work done by friction:
(1)
Where:
- Mass of the car, in kilogram.
- Initial velocity, in meters per second.
- Coefficient of friction, no unit.
- Travelled distance, in meters.
Then we derive an expression for the distance travelled by the vehicle:


As we notice, the distance travelled does not depend on the mass of the vehicle. Therefore, 
The cart is moving by simple harmonic motion, and its position at time t is described by

where
A is the amplitude of the oscillation

is the angular frequency
The amplitude of the oscillation corresponds to the maximum displacement of the spring, which corresponds to the initial position where the spring was released:
A=0.250 m
The period of the motion is T=5.67 s, and the angular frequency is related to the period by

Therefore now we can calculate the position of the system at the time t=29.6 s:
Answer:
0.45 m/s in the negative x-direction
Explanation:
From the law of conservation of momentum, the sum of initial momentum equals the sum of final momentum
Momentum, p=mv where m is the mass and v is the velocity
where
is the common velocity,
and
are velocities of magnet moving in positive x-direction and magnet moving in negative x-direction respectively,
and
are masses of magnet moving in positive x-direction and magnet moving in negative x-direction respectively.
Substituting 125 g for
and 85 g for
, 7.33 m/s
, -11.9 m/s for
then



Therefore, the velocity of single unit is 0.45 m/s in the negative x-direction
The resonance can be extended to wave phenomena.