Question

Which of the following describes an object in static equilibrium?

Answer 1

Answer:

A).  A platypus lies motionless on the sand.

Explanation:

As we know that equilibrium is defined as the system in the state of ZERO net force or zero acceleration condition.

So equilibrium is of two types

1) Static equilibrium : Here object will remain at rest and do not have any type of motion.

2) Dynamic equilibrium : Here object may move with constant speed in same direction so it will not have any acceleration.

So here

B.A tuna speeds up from 2 m/s to 3 m/s

C.A dolphin jumps out of the water

Not in equilibrium as speed is changing so acceleration is not zero

D.A zebra shark swims at a constant speed of 8 m/s

It is in dynamic equilibrium case where speed is constant

so correct answer will be

A.A platypus lies motionless on the sand.

Answer 2

A is the answer. If an object is at rest and is in a state of equilibrium, then we would say that the object is at static equilibrium. Static means stationary or at rest. A common physics lab is to hang an object by two or more strings and to measure the forces that are exerted at angles upon the object to support its weight.