Condition of Uniform Circular Motion

The angle between the direction of motion(blue) and direction and force(red)

Even if the force works, the speed does not change?

When an object moves linearly at a constant velocity, the force applied to the object is zero because there is no change in velocity. If so, is there a motion that has a force on an object but does not change its speed?
The correct answer is 'uniform circular motion'.

Uniform circular motion is a movement that keeps changing direction. In order to continue the circular movement, it is necessary to change the direction of the force constantly. This force is called centripetal force.