Answer:
B. An Iron Bar place in a room becomes cooler than its surroundings.
There are some missing information in the question.
However, since you are talking about magnetic force, I think you refer to the Lorentz force. When a particle of charge q and velocity v is immersed in a magnetic field of intensity B, the force acting on the particle is:

where

is the angle between the magnetic field and the direction of the particle.
Therefore, if force F is doubled, then also the velocity v must be double of its initial value:
The moon orbiting the Earth
Explanation:
The motion of the moon orbiting the earth is a circular motion. Circular motion is simply the motion of an object in circle at constant speed.
- A cannonball flying from a cannon is a projectile motion and not a circular motion.
- A car moving along a straight track is a linear/translational motion.
- Pendulum of a grandfather clock is a simple harmonic motion.
Learn more:
Circular motion brainly.com/question/2562955
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