Physics Concepts and Calculations Review

When an object is in motion, the most fundamental question about its movement relates to:

• The forces acting upon it

• The speed of the object

• The distance traveled

• The direction of the object

Calculation for force: F = mv²/r

• F = 0.5 × (4)²/2 = 8 N

• F = 0.5 × (3)²/2 = 4.5 N

• F = 1 × (4)²/2 = 8 N

• F = 0.5 × (5)²/2 = 12.5 N

When two objects interact, the forces they exert on each other are always equal in magnitude but opposite in direction.

• Newton's First Law states that an object at rest stays at rest unless acted upon by a net force.

• Newton's Second Law states that force equals mass times acceleration.

• Newton's Third Law states that for every action, there is an equal and opposite reaction.

• Newton's Law of Universal Gravitation states that every mass attracts every other mass.

A 75 kg hockey player slides on frictionless ice. If pushed with 150 N of force, what is the acceleration of the player?

• 1 m/s²

• 2 m/s²

• 3 m/s²

• 4 m/s²

Time for an object to fall from 200 m height.

• 3.2 s

• 4.5 s

• 5.1 s

• 6.0 s

An object's inertia is most directly related to its mass.

• Inertia is the resistance of any physical object to any change in its velocity.

• Inertia is the force that acts on an object in motion.

• Inertia is the speed of an object in a vacuum.

• Inertia is the weight of an object in a gravitational field.

An object's motion is determined by the vector sum (net force) of all forces acting upon it.

• This is described by Newton's first law of motion, F = ma.

• This is described by Newton's second law of motion, F = ma.

• This is described by Newton's third law of motion, F = ma.

• This is described by the law of universal gravitation, F = ma.

Average speed of a car traveling 120 km in 2 hours.

• 50 km/hr

• 60 km/hr

• 70 km/hr

• 80 km/hr

Circular motion involves continuous change in direction, requiring radial (centripetal) acceleration.

• Radial acceleration is directed towards the center of the circular path.

• Radial acceleration is directed away from the center of the circular path.

• Radial acceleration is constant in magnitude and direction.

• Radial acceleration is only present in linear motion.

A spacecraft moving at constant velocity in deep space experiences:

• No forces acting upon it

• A constant gravitational pull

• Friction from space dust

• Acceleration due to propulsion