when wire is coiled upon a nail then it will posses magnetic characteristics
This is due to the coiled shape it will behave like a solenoid and the magnetic field of solenoid is given as

so here when wire is coiled up on a nail then due to the magnetic field of the coil the nail will attain magnetic characteristic.
so correct answer will be
<em>Possess magnetic properties </em>
Answer:
the wagon should be used as frame of reference if an observer said the child was not moving.
Explanation:
The state of motion of a body depends upon the frame of reference. It is the set of co-ordinates according to which the motion is analyzed. If a child is riding in a wagon, then he will be considered in motion to a person standing outside the wagon. Hence, if we take a frame of reference outside the wagon then the child must be in motion with respect to the observer. On the other hand if the observer is inside the wagon, then the child must be in rest with respect to the observer. Hence, if we take the wagon to be the frame of reference, then the child will be at rest with respect to the observer.
<u>Therefore, the wagon should be used as frame of reference if an observer said the child was not moving.</u>
Answer:
Average speed = 5 m/s
Explanation:
Given the following data;
Distance = 100m
Time = 20 secs
To find the average speed;
Speed = distance/time
Substituting into the formula, we have;
Speed = 100/20
Speed = 5m/s
Therefore, Elsa's average speed is 5 meters per seconds.
To calcculate the braking force of the car moving, we use Newton's second law of motion which relates the acceleration and the force of an object moving. The force of an object moving is directly proportional to its acceleration and the proportionality constant is the mass of the object. It is expressed as:
Force = ma
Acceleration is the rate of change of the velocity of a moving object. We calculate acceleration from the velocity and the time given above.
a = (10 m/s) / 5 s = 2 m/s^2
So,
Force = ma
Force = 1000 kg ( 2 m/s^2 )
Force = 2000 kg m/s^2 or 2000 N
Answer:

Explanation:
When the rock is immersed in unknown liquid the forces that act on it are shown as under
1) Tension T by the string
2) Weight W of the rock
3) Force of buoyancy due to displaced liquid B
For equilibrium we have 
=
When the rock is suspended in air for equilibrium we have

When the rock is suspended in water for equilibrium we have
+
=
Using the given values of tension and solving α,β,γ simultaneously for
we get

Solving for density of liquid we get

