Phy 201-ch4-HW Due 03/05/18-class time A plastic ball in a liquid is acted upon
ID: 1582576 • Letter: P
Question
Phy 201-ch4-HW Due 03/05/18-class time A plastic ball in a liquid is acted upon by its weight and by a buoyant force. The weight of the ball is NaN N. The buoyant force has a magnitude of NaN N and acts vertically upward. An external force acting on the ball maintains it in a state of rest. The external force, including direction, is closest to: I. A) NaN N, downward B) NaN N, upward C) NaN N, upward D) NaN N, upward E) NaN N, downward Consider what happens when accurate statement? 2. you jump up in the air. Which of the following is the most A) I is the upward force exerted by the ground that pushes you up, but this force can never exceed your weight. B) You are able to spring up because the earth exerts a force upward on you which is stronger than the downward force you exert on the earth. C) Since the ground is stationary, it cannot exert the upward force necessary to propel you into the air. Instead, it is the internal forces of your muscles acting on your body itself which propels the body into the air. D) When you push down on the earth with a force greater than your weight, the earth will push back with the same magnitude force and thus propel you into the airExplanation / Answer
Question -1
Buoyant Force depends upon the volume displaced by the object and is given by
buoyant force =(density of liquid)(gravitational acceleration)(volume of liquid)
Since the plastic ball wieghs far less. but it displaces volume much higher, therefore the byoyant forces acted upwards will be far greater than the force exerted by gravity as its weith therefore there is a net upward force.
To maintain the ball at rest there is a force required downward equals to the diffrence of buoyant force and the gravitational force.
Hence direction (downwards) both a and e options are similiar, because there is no data given about any force so either of them can be an answer.
Question-2
In order to jump first of all we bend our thighs and put a pressure on earth downwards greater than our weight. Then according to the newton's third law earth exerts similar force(greater than our weight) upwards therefore we jump.
THus option-D is correct answer.