In physics, the inertial frame of reference is a very important concept.

He spends a lot of time for peacekeeping.

When an object is in free fall, its terminal velocity is determined by the balance between gravity and air resistance.

What is the initial velocity of this object?

He looked at the speedometer and checked the speed of the car.

He called me back immediately after he hung up the phone.

He loves physics and studies it in the library almost every day.

I am majoring in physical chemistry at university.

He is a world-famous physicist.

He understands the importance of learning.