Nonisolated Systems

Newton’s Laws

Applications of Newton’s Laws Gravity Conservation

of Energy

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QUESTION:

•When decelerating quickly in a car, you feel as if you are being thrown forward in your seat. Which one of Newton's Laws most directly explains this effect?

•a. Newton's first law b. Newton's second law •c. Newton's third law d. Newton's fourth law

ANSWER:

A

QUESTION:•What is Newton’s Second Law of Motion?A.E = mc2B.W = F*dC.F = maD.F = MLE.F = kN

ANSWER:

•C

QUESTION:In an upward accelerating elevator, what is the formula for the normal force (in terms of N, m, a, and g)? What is this force called?

ANSWER:

•N = ma + mg•Apparent Weight

QUESTION: A car with a mass of 1500 kg is being towed at a steady speed by a rope held at a 20o angle. A friction force of 320 N opposes the car’s motion. What is the tension in the rope?

ANSWER:•340 N

QUESTION:

•Type your question in here relating to Topic 1. As the Points get higher make questions harder.

ANSWER:

•(type answer here)

QUESTION:The coefficient of static friction is

A.smaller than the coefficient of kinetic friction.

B. equal to the coefficient of kinetic friction.

C. larger than the coefficient of kinetic friction.

D. not discussed in this chapter.

ANSWER:•C

QUESTION:Lisa, a runner, has purchased new shoes and wishes to measure the coefficient of static friction (s) between her shoes and the running track. She places a shoe on the tile and then slowly tilts the tile, measuring the angle at which the shoe just begins to move. Find an expression she can use to determine s in terms of .

ANSWER:

•s = tan

QUESTION:A trained sea lion slides from rest with constant speed down a 3-m-long ramp into a pool of water. If the ramp is inclined at angle of 36.9o above the horizontal and the coefficient of kinetic friction and static friction between the sea lion and the ramp is 0.25 and 0.50, respectively, what is the acceleration of the sea lion along the ramp? Use sin(36.9) = 0.6, cos(36.9) = 0.8, and g = 10 m/s2. a.6 m/s2 b. 10 m/s2 c. 0 m/s2 d. 2 m/s2 e. 4 m/s2 ANSWER:

•E

Since there’s constant speed,Fnet = 0 which implies that•-Fk + Fg,x= max of the sea lion•-FNμk + mgsin(36.9) = max

•Knowing FN = mgcos(36.9)•mgsin(36.9) - μkmgcos(36.9) = max

• Cancel the masses, m, and solve for a

QUESTION:Engineers are designing a curved section of a highway. The angle of the banked curve is 26.6o. What should be the radius of the curvature of the curve so that a car traveling at 20 m/s (~45 mph) will stay on the road without the aid of frictional forces (in case of icy condition)? Use sin(26.6) = 0.45, cos(26.6) = 0.90, tan(26.6) = 0.50, and g = 10 m/s2. a. 90 m b. 80 m c. 44 m d. 40 m e. 20 m

ANSWER:

•B

QUESTION:What is geometric shape of a planetary or satellite orbit?A. CircleB. HyperbolaC. SphereD. ParabolaE. EllipseANSWER:

•E

QUESTION:•Use Kepler’s third law to find Jupiter’s period from its semimajor axis a = 5.2 AU.

ANSWER:

•T = 12 years

QUESTION:•The figure shows a binary star system. The mass of star 2 is twice the mass of star 1. Compared to F(1on2) , the magnitude of the force F(2on1) isA.one quarter as big.B. half as big.C. the same size.D. twice as big.E. four times as big.ANSWER:

•C

QUESTION:Communication satellites appear to “hover” over one point on the earth’s surface. A satellite that appears to remain stationary as the earth rotates is said to be in a Geostationary orbit. What is the radius of the orbit of such a satellite?•Use G = 6.67x10-11, M (earth) = 5.98x1024

ANSWER:•4.22x107 m

QUESTION:Saturn, at 5.68x1026 kg, has nearly 100 times the mass of the earth. It is also much larger, with a radius of 5.85x107 m. What is the value of g on the surface of Saturn?Use G = 6.67x10-11

ANSWER:

•11.1 m/s2

3 m

4 m

5 m

QUESTION:When a force of 120.0 N is applied to a certain spring, it causes a stretch of 2.25 cm. What is the potential energy of this spring when it is compressed by 3.50 cm?

ANSWER:•3.26 J

QUESTION:A particle with the potential energy shown in the graph is moving to the right. It has 1 J of kinetic energy at x = 1 m. It has 1 J of kinetic energy at x = 1 m. Where is the particle’s turning point?ANSWER:

X = 6 m

QUESTION:Explain what mechanical energy is when it is conserved in a system.

ANSWER:E = K + UEi = EfKf + Uf = Ki + Ui

QUESTION:•What is the comprehensive equation for the energy of a system?A.W = Fdcos(θ)B.Ei = Ef

C.E = K + UD.ΔEsys = ΔK + ΔU + ΔEth

E.ΔEsys = W + K + U

ANSWER:

•D

QUESTION:What is the equation for work?A.W = FmaB.W = Fcos(θ)C.W = FΔrcos(θ)D.W = F – Wd

ANSWER:•C

QUESTION:A crane lowers a steel girder into place at a construction site. The girder moves with constant speed. Consider the work Wg done by gravity and the work WT done by the tension in the cable. Which of the following is correct?A. Wg and WT are both zero.

B. Wg is negative and WT is negative.

C. Wg is negative and WT is positive.

D. Wg is positive and WT is positive.

E. Wg is positive and WT is negative.

ANSWER:

E

QUESTION:

ANSWER:

•A

• Energy equation of a system: K + U + Eth = Wext.

friction th kW E f s

QUESTION:You are behind a 1500 kg truck traveling at 60 mph (27 m/s).To pass it, you speed up to 75 mph (34 m/s) in 6.0 s.What power is required to do this? ( Remember, K + U + Eth =Esys = Wext)

ANSWER:•53,000 W