The limiting friction tries to stop the cart . but later the rolling friction makes it easier to move.

Introduction:
The force needed to start a cart is somewhat greater than the force needed to keep it moving with uniform speed. This phenomenon can be explained by examining the concept of static and kinetic friction.

Explanation:
1. Static Friction:
When a cart is at rest, it experiences static friction, which is the force that opposes the initial motion of an object. Static friction is generally higher than kinetic friction, the force that opposes the motion of an object that is already in motion.

2. Overcoming Static Friction:
To start a cart, a force greater than the static friction must be applied. This force is known as the force of inertia or the force required to overcome the initial resistance to motion. The resistance to motion is caused by factors such as roughness between the wheels and the ground, imperfections in the surface, and the weight of the cart.

3. Role of Inertia:
Inertia is the tendency of an object to resist changes in its state of motion. When the cart is at rest, it has inertia in the form of static friction. This static friction must be overcome to initiate motion. The greater the mass of the cart, the greater the inertia, and consequently, the greater the force needed to start the cart.

4. Transition to Kinetic Friction:
Once the cart starts moving, the static friction is replaced by kinetic friction. Kinetic friction is generally lower than static friction, making it easier to keep the cart moving at a uniform speed. Kinetic friction opposes the motion of the cart but is generally constant as long as the speed remains constant.

5. Factors Affecting Force Required:
The force required to start a cart depends on several factors, including the weight of the cart, the roughness of the surface, and the presence of any external forces acting on the cart. Additionally, the force required may vary depending on the initial acceleration desired and the presence of any incline or decline in the surface.

Conclusion:
In summary, the force needed to start a cart is somewhat greater than the force needed to keep it moving with uniform speed due to the presence of static friction, which resists the initial motion. Once the cart overcomes this static friction and starts moving, it experiences kinetic friction, which is generally lower and allows for easier maintenance of a uniform speed. Several factors, including weight, surface roughness, and external forces, can affect the force required to start the cart.