Deck 5: Energy: Part A

Question 1

An airplane in a wide sweeping "outside" loop can create 0-g inside the aircraft cabin.What must be the radius of curvature of the flight path for an aircraft moving at 180 m/s to create a condition of "weightlessness" inside the aircraft?

A) 1150 m
B) 1800 m
C) 2300 m
D) 3300 m

Answer 1

3300 m

Question 2

If a planet has 9 times the radius of the Earth,but has the same density as the Earth,what is the gravitational acceleration at the surface of the planet? (g = 9.8 m/s²)

A) 29.4 m/s²
B) 88.2 m/s²
C) 265 m/s²
D) 39.2 m/s²

Answer 2

88.2 m/s²

Question 3

An Earth satellite is orbiting at a distance from the Earth's surface equal to two Earth radii.At this location,the acceleration due to gravity is what factor times the value of g at the Earth's surface?

A) There is no acceleration since the satellite is in orbit.
B) 1/9
C) 1/4
D) The answer is not given.

Answer 3

1/9

Question 4

A point on the rim of a 0.30-m radius rotating wheel has a tangential speed of 4.0 m/s.What is the tangential speed of a point 0.10 m from the center of the same wheel?

A) 1.0 m/s
B) 1.3 m/s
C) 2.7 m/s
D) 8.0 m/s

Question 5

The distance from the center of a Ferris wheel to a passenger seat is 6.0 m.What centripetal acceleration does a passenger experience when the wheel rotates once every 4π seconds?

A) 16.9 m/s²
B) 9.0 m/s²
C) 3.0 m/s²
D) 1.5 m/s²

Question 6

In order to train for a high-g environment,an astronaut is placed in a centrifuge of radius several meters and rotated in a horizontal circle at constant speed.In this situation,in which direction is the net force on the astronaut?

A) The net force is down since gravity cannot be turned off.
B) The net force is horizontal toward the center of the circle.
C) The net force is between horizontal toward the center of the circle and straight up,the angle depending on the speed and the radius involved.
D) The net force is zero since the astronaut is moving at constant speed and thus the force has no direction.

Question 7

How many revolutions per second are needed for a centrifuge to produce an acceleration of 1 200g at a radius arm of 15.0 cm?

A) 40.7 rev/s
B) 44.6 rev/s
C) 81.4 rev/s
D) 151 rev/s

Question 8

What centripetal force does an 60-kg passenger experience when seated 12 m from the center of a Ferris wheel that rotates once every 4π seconds?

A) 484 N
B) 180 N
C) 914 N
D) 240 N

Question 9

At what speed will a car round a 125 m radius curve,banked at a 45° angle,if no friction is required between the road and tires to prevent the car from slipping? (g = 9.8 m/s²)

A) 27 m/s
B) 17 m/s
C) 23 m/s
D) 35 m/s

Question 10

A roller coaster,loaded with passengers,has a mass of 3000 kg;the radius of curvature of the track at the bottom point of the dip is 24 m.If the vehicle has a speed of 18 m/s at this point,what force is exerted on the vehicle by the track? (g = 9.8 m/s²)

A) 2.3 × 10⁴ N
B) 4.7 × 10⁴ N
C) 7.0 × 10⁴ N
D) 1.0 × 10⁴ N

Question 11

A 0.40-kg mass,attached to the end of a 0.75-m string,is whirled around in a circular horizontal path.If the maximum tension that the string can withstand is 400 N,then what maximum speed can the mass have if the string is not to break?

A) 370 m/s
B) 27 m/s
C) 19 m/s
D) 29 m/s

Question 12

An object of mass 0.50 kg is transported to the surface of Planet X where the object's weight is measured to be 10 N.The radius of the planet is 4.0 × 10⁶ m.What is the mass of Planet X? (G = 6.67 × 10−¹¹ N × m²/kg²)

A) 13 × 10¹⁹ kg
B) 17 × 10²² kg
C) 9.6 × 10²⁴ kg
D) 4.8 × 10²⁴ kg

Question 13

An object of mass 0.50 kg is transported to the surface of Planet X where the object's weight is measured to be 10 N.The radius of the planet is 4.0 × 10⁶ m.What free fall acceleration will the 0.50 kg object experience when at the surface of Planet X?

A) 48 m/s²
B) 20 m/s²
C) 16 m/s²
D) 40 m/s²

Question 14

A cylindrical space colony 13 km in diameter and 30 km long has been proposed as living quarters for future space explorers.Such a habitat would have cities,land,and lakes on the inside surface and air and clouds in the center.All this would be held in place by the rotation of the cylinder about the long axis.How fast would such a cylinder have to rotate at its perimeter to produce a 1-g gravitational field at the walls of the cylinder?

A) 200 m/s
B) 250 m/s
C) 650 m rad/s
D) 800 m rad/s

Question 15

A ventilation fan has blades 0.50 m long rotating at 20 rpm.What is the centripetal acceleration of a point on the outer tip of a blade?

A) 1.1 m/s²
B) 2.2 m/s²
C) 0.55 m/s²
D) 3.3 m/s²

Question 16

An object of mass 0.50 kg is transported to the surface of Planet X where the object's weight is measured to be 10 N.The radius of the planet is 4.0 × 10⁶ m.What free fall acceleration will the 0.50 kg object experience when transported to a distance of 2.0 × 10⁶ m from the surface of this planet?

A) 90 m/s²
B) 8.9 m/s²
C) 13 m/s²
D) 18 m/s²

Question 17

A point on the rim of a 0.25-m radius fan blade has centripetal acceleration of 0.20 m/s².Find the centripetal acceleration of a point 0.1 m from the center of the same wheel.

A) 0.01 m/s²
B) 0.02 m/s²
C) 0.04 m/s²
D) 0.08 m/s²

Question 18

A 1500-kg car rounds an unbanked curve with a radius of 52 m at a speed of 14 m/s.What minimum coefficient of friction must exist between the road and tires to prevent the car from slipping? (g = 9.8 m/s²)

A) 0.18
B) 0.30
C) 0.28
D) 0.38

Question 19

The cutting cord on a gas-powered weed cutter is 0.20 m in length.If the motor rotates at the rate of 20 rev/s,what is the tangential speed of the end of the cord?

A) 628 m/s
B) 25 m/s
C) 19 m/s
D) 63 m/s

Question 20

At what angle (relative to the horizontal)should a curve 52 m in radius be banked if no friction is required to prevent the car from slipping when traveling at 10 m/s? (g = 9.8 m/s²)

A) 28°
B) 32°
C) 16°
D) 11°

Question 21

An object when orbiting the Earth at a distance of three Earth radii from the center of the Earth has a weight of 2.0 N.What is the object's mass? (g at the surface of the Earth is 9.8 m/s²)

A) 0.10 kg
B) 1.8 kg
C) 0.92 kg
D) 1.0 kg

Question 22

A careful photographic survey of Jupiter's moon Io by the spacecraft Voyager 1 showed active volcanoes spewing liquid sulfur to heights of 60 km above the surface of this moon.If the value of g on Io is 2.0 m/s²,estimate the speed with which the liquid sulfur left the volcano.

A) 120 m/s
B) 240 m/s
C) 490 m/s
D) 970 m/s

Question 23

If the mass of Venus is 0.786 times that of Earth,and its radius is 0.950 that of Earth,estimate the gravitational acceleration g at the surface of Venus.(g_earth = 9.80 m/s²)

A) 7.31 m/s²
B) 3.73 m/s²
C) 8.27 m/s²
D) 8.53 m/s²

Question 24

Geosynchronous satellites orbit the Earth at a distance of 42,000 km from the Earth's center.Their angular speed at this height is the same as the rotation rate of the Earth,so they appear stationary at certain locations in the sky.What is the force acting on a 2000-kg satellite at this height? The radius of the Earth is
)(Hint: Use that gravity behaves as
) )

A) 85 N
B) 333 N
C) 411 N
D) 455 N

Question 25

The acceleration due to gravity at the surface of Planet X is 10 m/s².What is the acceleration due to gravity at an altitude of 4000 km above the surface of this planet?

A) 10 m/s²
B) 8.0 m/s²
C) 4.4 m/s²
D) More information is needed.

Question 26

Two satellites are monitored as they orbit the Earth;satellite X is four times as far from the Earth's center as is satellite Y.From Kepler's third law one may conclude that the period of revolution of X is what factor times that of Y?

A) 1/2
B) 2.0
C) 8.0
D) 22.6

Question 27

An asteroid in orbit about the Sun has a linear speed of 4 km/s when at a distance of closest approach d from the sun.What is its linear speed when it is at its greatest distance from the sun,a distance 4d?

A) 1 km/s
B) 2 km/s
C) 8 km/s
D) 16 km/s

Question 28

At an altitude of 3 times the radius of the Earth,the acceleration due to gravity is

A) g/3.
B) g/9.
C) g/27.
D) not given.

Question 29

A double star system with each star having the mass of the Sun has an orbital period of 1 year.A second double star system,also with each star having the mass of the Sun,has an orbital period of 8 years.If the separation of the stars in the first system is d and the orbits in both cases are circular,what is the separation of the stars in the second system?

A) 0.5d
B) 2d
C) 4d
D) 8d

Question 30

A satellite is in a circular orbit about the Earth at a distance of two Earth radii above the surface.What is the speed of the satellite? (The radius of the Earth is 6.4 × 10⁶ m,and G = 6.67 × 10−¹¹ N × m²/kg². )

A) 2 800 m/s
B) 4 600 m/s
C) 5 600 m/s
D) 16 800 m/s

Question 31

An observation satellite for mapping purposes is placed in a low Earth orbit.In order to see the whole surface of the Earth,which would be the preferred orbit?

A) an equatorial orbit
B) a polar orbit
C) an orbit inclined 45° to the equator
D) It doesn't matter since the Earth turns completely every 24 hours.

Question 32

At what location does an artificial Earth satellite in elliptical orbit have its lowest speed?

A) nearest the Earth
B) farthest from the Earth
C) between Earth and Moon
D) between Earth and Sun