Because the floor is firm, and will not move from the ball.
Does a ball rebound when it strikes a soft substance?
No; it does not rebound when it strikes a soft substance, like a heap of wool or feathers.
Are solids ever elastic?
Yes; many solids are elastic.
Name some articles useful from their elastic properties.
Watch-springs, wagon-springs, steel pens, and spring seats are very useful.
Why does a wooden bow throw an arrow from it?
When the force that bends the bow is removed, it springs back to its former shape, and in so doing throws the arrow from it.
Can metals be bent?