Question

1. You drop a wooden cork from a height of a few feet above the water. The positive direction is defined as upwards.

While the cork is fully submerged and moving downward (after it has fully submerged in the water), the sign of the cork's velocity is ___ ["positive", "negative", "zero"]         , and the sign of the cork's acceleration is ______ ["positive", "negative", "zero"]

2. You drop a wooden cork from a height of a few feet above the water. The positive direction is defined as upwards.

While the cork is at its lowest point in the water, the sign of the cork's velocity is ___ ["positive", "negative", "zero"] and the sign of the cork's acceleration is ____

3. You drop a wooden cork from a height of a few feet above the water. The positive direction is defined as upwards.

While the cork moves upwards towards the surface, the sign of the cork's velocity is ["postive", "negative", "zero"], and the sign of the cork's acceleration is ____

4. You drop a wooden cork from a height of a few feet above the water. The positive direction is defined as upwards.

While the cork floats at rest on the surface, the sign of the cork's velocity is ___ ["positive", "negative", "zero"] and the sign of the cork's acceleration is ___

5. Which kind of flow consists of streamlines?

a	turbulent flow

b	laminar flow

c eddy currents

Answer 1

1. Sign of cork's velocity is negative and sign of cork's acceleration is positive. (Because velocity is in downward direction whereas upward is taken as positive and cork will be deccelrating so sign of acceleation should be opposite to that of velocity.)

2. Cork's velocity is Zero and sign of cork's acceleration is positive. (At the lowest point cork is momentarily at rest while net force i.e. resultant of upthrust and weight is in upward direction, so accelration is upward and hence positive.)

3.Sign of cork's velocity is positive and sign of cork's acceleration is also positive. (As both are in upward direction.)

4. When cork float's on the surface sign of cork's velocity is zero and that of acceleratio is also zero. (As the cork is floating neither moving up or down so velocity is zero further it is in equilibrium whenfloating i.e. net force on it is zero so its acceleraion is also zero.)

5. Kind of flow consists of streamlines is b. laminar flow. (It is according to definition of streamlines)