Q&A Hero

Q: The potential energy of a pendulum is least A) when its potential energy is greatest. B) at the top of its swing. C) at the bottom of its swing. D) when its total energy is greatest.

Q: The kinetic energy of a pendulum is greatest A) when its potential energy is greatest. B) at the top of its swing. C) at the bottom of its swing. D) when its total energy is greatest.

Q: A student weighing 300 N climbs a flight of stairs 7.0 m high in 8 s. What power is required to perform this task? A) 2100 J B) 2400 J C) 2100 W D) 2400 W E) 38 W

Q: A student weighing 200 N climbed a flight of stairs 9.0 m high in 4 s. How much work was done by the student? A) 1800 J B) 800 J C) 1800 W D) 800 W E) 50 W

Q: An 3000-kg car traveling at 70 m/s takes 8 m to stop under full braking. The same car under similar road conditions, traveling at 140 m/s, takes ______________ m to stop under full braking. A) 16 B) 3 C) 8 D) 32 E) 18

Q: When an 6-kg object increases its potential energy by 540 J, approximately how has its position changed? A) It has risen vertically 9 m. B) It has fallen vertically 9 m. C) It has risen vertically 90 m. D) It has moved horizontally 90 m.

Q: A 8-kg object moves vertically a distance of 3 m. Its potential energy has changed by approximately how much? A) It has increased by 24 J. B) It has decreased by 240 J. C) It has decreased by 24 J. D) It has increased by 240 J.

Q: An object has kinetic energy of 324 J. If its speed is 9 m/s, what is its mass? A) 8 B) 36 C) 648 D) 324

Q: An object of mass 6 kg has a speed of 4 m/s and moves a distance of 2 m. What is its kinetic energy in joules? A) 48 B) 24 C) 17 D) 12

Q: The energy of motion is called A) inertia. B) power. C) kinetic energy. D) potential energy.

Q: The quantity is known as A) kinetic energy. B) potential energy. C) work. D) energy. E) power.

Q: Which of the following is a vector quantity? A) Force B) Power C) Work D) Time E) None of these

Q: Which of the following is a vector quantity? A) Energy B) Power C) Work D) None of these

Q: The ______________ distance is used in calculating work. A) normal B) square of C) perpendicular D) parallel

Q: Work requires A) motion. B) zero net force. C) zero momentum. D) a force perpendicular to the direction of motion.

Q: Which of the following is not a unit of work? A) ft lb B) N m C) joule D) watt

Q: A joule per second (J/s) is a A) Watt. B) Newton. C) Kilogram. D) Second.

Q: A joule/meter (J/m) is a unit of A) force. B) work. C) energy. D) power.

Q: Work is defined as force times A) distance. B) time. C) parallel distance. D) perpendicular distance.

Q: A comet is traveling at a speed of 50,000 mi/h when it is 100 million miles from the Sun. Compute its speed when it is 25 million miles from the Sun.

Q: What is the purpose of having automobile air bags?

Q: It is generally easier to push an object once it is moving than when one is getting it started. Why is this?

Q: When you push on a stationary object and it doesn't move, what kind of force is most likely to be opposing your efforts?

Q: A 0.065-kg bullet travels with a velocity of magnitude 90 km/h. What is the bullet's linear momentum?

Q: A stationary but movable 450-kg cannon is fired, and the 12-kg cannonball moves off to the right with a velocity of 20.0 m/s. What is the cannon's velocity (neglecting friction or any restraints)?

Q: Two carts (A's mass = 4.5 kg and B's mass = 1.5 kg) are held against a strong, compressed spring. The carts are released simultaneously, and B moves off to the right with a speed of 2.0 m/s. What is A's initial velocity?

Q: To increase the force of gravity between two masses by a factor of 9, how would the objects have to be moved?

Q: A 6.0-kg object exerts a force of 8.0 N on a 2.0-kg object. What is the magnitude of the force on the 6.0-kg object?

Q: Calculate the centripetal force on a 3.0-kg object moving in a horizontal circular path of 20-m radius with a speed of 8.0 m/s.

Q: A force of 100 N applied to an object produces an acceleration of 4.00 m/s2. Determine the force needed to give the object an acceleration of 16.0 m/s2.

Q: An automobile with a mass of 2000 kg is moving north on a level, straight highway with a constant velocity of 80 km/h. What is the unbalanced force acting on the automobile?

Q: Calculate the force on a string tied to a ceiling with a 9.0-kg mass attached.

Q: What is the force of gravity acting on a 1-kg mass? (g = 9.8 m/s2)

Q: What is the mass in kilograms of an astronaut on the Moon who weighs 185 lb on Earth?

Q: An unbalanced force of 30 N is applied to a mass of 5.0 kg. What will be the resulting acceleration?

Q: The law of conservation of angular momentum states that the angular momentum of an object remains constant if there are no external ______________ torques acting.

Q: The linear momentum of an object is conserved if there are no ______________ forces acting on it.

Q: Angular momentum has units of ______________.

Q: G (big G) is not a(n) ____________, as g (little g) is.

Q: Linear momentum has units of ______________.

Q: Linear momentum is the product of mass times ______________.

Q: Newton's law of gravitation applies to all ______________.

Q: For Newton's third law, the action and reaction forces are equal in magnitude and ______________ in direction.

Q: ______________ is the symbol for the universal gravitational constant.

Q: In Newton's law of universal gravitation, F = Gm1m2/r2 for uniform objects, the quantity r is______________.

Q: A(n) ______________ force is necessary for uniform circular motion.

Q: Newton's third law of motion states that whenever one object exerts a force upon a second object, the second object exerts a(n) ______________ and ______________ force upon the first object.

Q: Jet propulsion can be explained in terms of Newton's third law and the ______________.

Q: A student stands on a chair. The forces acting on her or him are supplied by gravity acting downward and by the ______________ acting upward.

Q: For Newton's third law, the action and reaction forces are equal in ______________ and opposite in direction.

Q: Newton's third law force pair acts on ______________ objects.

Q: An apple weighs approximately one ______________.

Q: In the SI, weight is expressed in units of ______________.

Q: The acceleration of an object with a zero net force acting on it is ______________.

Q: Forces always occur in ____________.

Q: An astronaut on the Moon has the same mass as when on Earth,but has a different ____________.

Q: In keeping with Newton's second law of motion, if the force acting on a moving object is doubled, then its ______________ is doubled.

Q: The natural tendency of an object to remain at rest or in uniform straight-line motion is called _____________.

Q: An indication of an object's inertia is given by its ______________.

Q: a = F/m is a statement of ______________.

Q: An acceleration is evidence of ______________.

Q: Force is a(n) ______________ quantity.

Q: A quantity that is capable of producing motion or a change in motion is called a(n) ______________.

Q: To initiate motion, a(n) ____________ force is necessary.

Q: A change in motion requires a(n) ____________.

Q: The speed of a comet in its orbit around the Sun is ______________ when its distance from the Sun is least (perihelion). A) zero B) reversed C) greatest D) least

Q: The speed of a comet in its orbit around the Sun is ______________ when its distance from the Sun is greatest (aphelion). A) zero B) reversed C) greatest D) least

Q: The angular momentum of a body is constant if the A) net torque is zero. B) net force is constant. C) net torque is constant. D) net force is zero.

Q: The total linear momentum of an isolated system of masses remains the same if there are no external ______________ acting on the system. A) forces B) torques C) unbalanced forces D) unbalanced torques

Q: What must be exerted on an object to change the angular momentum? A) Linear momentum B) Torque C) A force parallel to the motion D) Inertia

Q: In an equation, the symbol m generally stands for A) inertia. B) torque. C) momentum. D) mass. E) meters.

Q: The angular momentum of a 30.0 kg object moving around a 50.0 m circle at a constant speed of 2.70 m/s is A) 0.0 N B) 4050 N C) 109 N D) 81 N

Q: The linear momentum of a 40.0 kg object moving around a 90.0 m circle at a constant speed of 7.60 m/s is A) 0.0 N B) 304 N C) 1155 N D) 27360 N

Q: Linear momentum A) has the units of mass times acceleration. B) has magnitude and direction. C) is a scalar quantity. D) none of these

Q: The quantity mvr is an object's A) inertia. B) torque. C) linear momentum. D) angular momentum.

Q: The linear momentum of an object can be determined by taking the product of the mass and the A) acceleration of the object. B) velocity of the object. C) distance the object moves. D) displacement of the object.

Q: The force required to move a 50.0 kg object in a 55.0 m circle at a constant speed of 2.60 m/s is A) 0.0 N B) 6.1 N C) 0.12 N D) 2.36 N

Q: To cause an object to move in a circle, a ______________ force is necessary. A) balanced B) functional C) centripetal D) centrifugal

Q: The acceleration of an object acted on by a net force perpendicular to the direction of the object's original motion A) causes a change in direction. B) is described by Newton's laws. C) causes a change in velocity. D) all of these

Q: The variables m1and m2 that appear in the equation F = Gm1m2/r2 are A) the straight-line distance between the centers of each object. B) the rate at which each object is moving. C) the mass of each object. D) the diameter of each object.