Because under your thumb, inside the straw, there is now a vacuum which keeps the water in.
there is no air
When you press the top of the straw with your thumb or finger tip, the pressure you apply traps air inside the straw, preventing the water from dripping out. The pressure you exert keeps the water forced inside the straw despite gravity trying to pull it down.
When you press the top of the straw with your thumb, you create a seal which prevents air from entering the straw. The pressure inside the straw increases, causing the water to remain inside the straw due to the force of gravity and the seal created by your thumb.
Your finger prevents air from entering through the top of the straw. As fluid moves down the straw it leaves a void in it's wake, one that is usually immediately filled by air. By preventing the air from entering the top of the straw, the fluid cannot move downwards because to do so would leave a vacuum space between your finger and the fluid; this "sucks" the fluid back in into place and prevents it from decending down the straw.
Lowest - Left hand - thumb(1st finger), 2nd finger, 3rd finger and 4th finger Right Hand - 2nd finger, 3rd finger and 4th finger (no pinky) Middle - LH - thumb, 3rd finger, 4th finger RH - 2nd finger, 3rd finger and 4th finger (no pinky) Top - LH - thumb, 3rd finger and 4th finger RH - none
The thumb is called a thumb instead of a finger because it is smaller than a finger. A thumb also has 2 joints and a finger has 3.
It's a matter of air pressure that acts on the water. When the straw is uncovered, there are two forces acting on the water inside. There is gravity, pulling the water down, and air pressure. The pressure is about the same on both ends of the straw, but on the top of the straw, the pressure pushes the water downward, and on the bottom of the straw, the pressure pushes upward. Both of the pressures are the same, so the net force is just the force of gravity pulling the water down and out of the straw. When you cover the top of the straw, you block the air from pushing down on the water. In this case, the only forces on the water are the air pressure pushing up, and gravity pulling down. However, the air pressure is a greater force than gravity, and keeps the water in the straw despite gravity's pull.
Your forefinger is your pointer or index finger. It is the finger next to your thumb.
No. When the body is in the anatomical position, the thumb is further away from the midline. You say that the thumb is lateral to the ring finger.
It is the measurement between the thumb and middle finger, thumb and ring finger and middle finger to ring finger.
Finger next to the thumb, i.e. To the immediate right of the thumb on your right hand To the immediate left of the thumb on your left hand
Everyone thinks that your middle finger is the longest finger on your hand, but according to doctors, the thumb (which is counted as a finger) is the longest. Your thumb does not end at the crease, it ends at the bone close to your wrist. your thumb is the longest finger on your hand!