Jeopardy Jeopardy PHY101 Chapter Two Review Newton’s Laws

Study of Newton’s Laws Basics of Force Newton’s Laws Analyzing Forces Circular Motion Resistive Forces Potpourri $100 $200 $300 $400

Basics of Force $100 What is Force? ANSWER

Basics of Force $200 What is the equation for force? What are the units in the 3 systems?

What is weight? ANSWER Basics of Force $300

ANSWER Basics of Force $400 What is momentum?

Newton's Laws $100 ANSWER What is mass?

Newton's Laws $200 ANSWER What is Newton’s First Law?

Newton's Laws $300 ANSWER What is Newton’s 2nd Law?

Newton's Laws $400 ANSWER What is Newton’s 3rd Law?

Analyzing Forces $100 ANSWER What is a free body diagram?

Analyzing Forces $200 ANSWER What is a normal force?

Analyzing Forces $300 ANSWER What is Hooke’s Law?

Analyzing Forces $400 ANSWER A child stands on a bathroom scale while riding in an elevator. The child's weight when the elevator is not moving is 200 N. What is the child’s mass in kg? What does the scale read (tension T) when the elevator accelerates upward at 1.00 m/s 2 ?

Circular Motion $100 ANSWER If an object moves in a circle, what kind of force acts the centripetal force?

Circular Motion $200 ANSWER What is the equation for centripetal (radial) force?

Circular Motion $300 ANSWER What is Newton’s Law of Gravity?

Circular Motion $400 ANSWER What is the acceleration due to the earth's gravity at a distance of one earth radius above the earth's surface? a. 2.5 m/s²b. 5 m/s²c. 10 m/s²d. 20 m/s²

Resistive Forces $100 ANSWER What is a drag force?

ANSWER Resistive Forces $200 What is friction?

ANSWER Resistive Forces $300 Name two types of friction?

ANSWER Resistive Forces $400 A horizontal force of 640 N is applied to a car with a mass of 1600 kg. What is the acceleration of the car if the coefficient of rolling friction is 0.01? a m/s²b m/s²c. 0.2 m/s²d. 0.3 m/s²

Potpourri $100 ANSWER A 9.00-kg object is moving in a circle with a constant speed of 45.0 m/s. If the circular path has a radius of 20.0 m, what is the net force on the object?

Potpourri $200 ANSWER What are the conditions for simple harmonic motion?

Potpourri $300 ANSWER Before going to the beach, you check the position of the moon. Why?

Potpourri $400 ANSWER The average orbital speed of Mars is 2.41 x 10 4 m/s. If the radius of Mars's orbit is 2.28 x m, how long does it take Mars to complete one orbit?

Basics of Force $100 Answer Back to Jeopardy What is Force? Force is a push or a pull.

Basics of Force $200 Answer Back to Jeopardy What is the equation for force? Force = F = ma = m  v /  t SI unit 1 kg*m/s² = 1 Newton = 1 N cgs unit 1 g*cm/s² = 1 dyne Common unit 1 slug*ft/s² = 1 lb. 1 N = 10 5 dynes = lbs

Basics of Force $300 Answer Back to Jeopardy What is weight? Weight is the force of gravity acting on a body. W = mg where g is local gravity

Basics of Force $400 Answer Back to Jeopardy What is momentum? Momentum is mass X velocity p = mv Unit is 1 kg*m/s in SI

Newton's Laws $100 Answer Back to Jeopardy What is mass? Mass is a measure of an object’s resistance to acceleration. It is a measure of the quantity of matter in an object.

Newton's Laws $200 Answer Back to Jeopardy What is Newton’s First Law? An object will remain at rest or in motion with a constant velocity unless acted upon by an outside force.  F = 0 v = constant a = 0

Newton's Laws $300 Answer Back to Jeopardy What is Newton’s 2nd Law? An object is accelerated whenever a net external force acts on it. The net force equals the objects mass times its acceleration.  F = ma

Newton's Laws $400 Answer Back to Jeopardy What is Newton’s 3rd Law? Forces always come in pairs. When one object exerts a force on a second object, the second exerts an equal and opposite force on the first.  F = 0 F 12 = -F 21

Analyzing Forces $100 Answer Back to Jeopardy What is a free body diagram? A free body diagram is a force picture showing all the forces, the net acceleration and the direction of motion.  F y = ma = T - mg T a T = mg + ma T = m(g + a) mg

Analyzing Forces $200 Answer Back to Jeopardy What is a normal force? A normal force is a (reactive) balancing force such that  F = 0.

Analyzing Forces $300 Answer Back to Jeopardy What is Hooke’s Law? This is a conservative spring force equation.  F= - k S x = ma where k S = Weight of spring & object/stretch in SI units of N/m

Analyzing Forces $400 Answer Back to Jeopardy A child stands on a bathroom scale while riding in an elevator. The child's weight when the elevator is not moving is 200 N. What is the child’s mass in kg? m = Weight/g = 20.4 kg What does the scale read (tension T) when the elevator accelerates upward at 1.00 m/s 2 ?  Fy= ma = T - mg T = mg + ma T = m(g + a) = 220 N

Circular Motion $100 Answer Back to Jeopardy If an object moves in a circle, what kind of force acts the centripetal force? A real force like tension or gravity must act as a centripetal force and point toward the center of the circle.

Circular Motion $200 Answer Back to Jeopardy What is the equation for centripetal (radial) force?  F centripetal = mv²/r

Circular Motion $300 Answer Back to Jeopardy What is Newton’s Law of Gravity? F = G m 1 *m 2 /d² G = 6.67 * N*m²/kg²

Circular Motion $400 Answer Back to Jeopardy What is the acceleration due to the earth's gravity at a distance of one earth radius above the earth's surface? a.2.5 m/s²b. 5 m/s²c. 10 m/s²d. 20 m/s² F = G M*m/d² = mg If d new = 2d, then F NEW = G M*m/(4d²) = mg NEW = mg/4 g NEW = g/4 = 2.45 m/s²

Resistive Forces $100 Answer Back to Jeopardy What is a drag force? A resistive force called air resistance. Drag Force = ½ C*density*Area*v²

Resistive Forces $200 Answer Back to Jeopardy What is friction? A force of resistance to relative motion between 2 bodies or substances in physical contact. f = Coefficient of friction *Normal Force = µF N

Resistive Forces $300 Answer Back to Jeopardy Name two types of friction? Static friction no motion Kinetic friction motion

Resistive Forces $400 Answer Back to Jeopardy A horizontal force of 640 N is applied to a car with a mass of 1600 kg. What is the acceleration of the car if the coefficient of rolling friction is 0.01? a m/s²b m/s²c. 0.2 m/s²d. 0.3 m/s²  F y = 0 = F N – mg F N = mg = N f K = µF N = µmg = 157 N  F X = ma = Pull – f k = 640 N – 157 N = 483 N a =  F X /m = 483 N/ 1600 kg = 0.30 m/s²

Potpourri $100 Answer Back to Jeopardy A 9.00-kg object is moving in a circle with a constant speed of 45.0 m/s. If the circular path has a radius of 20.0 m, what is the net force on the object? F = mv²/r = (9.00kg)*(45 m/s)²/(20.0m) = 911 N

Potpourri $200 Answer Back to Jeopardy What are the conditions for simple harmonic motion? 1.Motion must be periodic 2.Force must cause the motion and be parallel to it.

Potpourri $300 Answer Back to Jeopardy Before going to the beach, you check the position of the moon. Why? Low tide = moon on horizon High tide = high point in sky

Potpourri $400 Answer Back to Jeopardy The average orbital speed of Mars is 2.41 x 10 4 m/s. If the radius of Mars's orbit is 2.28 x m, how long does it take Mars to complete one orbit? V = 2  r/T T = 2  r/v = 5.94 * 10 7 sec = 688 days

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