4.1

4.2

4.3 F = m a Force = mass x acceleration

4.4

4.5

4.6

4.7 Force = mass x acceleration F = m a 2 nd law: “The acceleration of an object is directly proportional to the net force acting on the object and is in the direction of the net force and is inversely proportional to the mass of the object”

4.8 Force = mass x acceleration F = m a

4.9

4.10

Questions -- MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question.

4.12 1) A 10-kg brick and a 1-kg book are dropped in a vacuum. The force of gravity on the 10-kg brick is A) zero. B) the same as the force on the 1-kg book. C) 10 times as much as the force on the 1-kg book. 2) Neglecting friction, a large block of ice and a small block of ice start sliding down an incline together. The heavier block will get to the bottom A) after the light block. B) at the same time as the light block. C) before the light block.

4.13 3) The force required to maintain an object at a constant velocity in free space is equal to A) the mass of the object. B) zero. C) the weight of the object. D) the force required to stop it. E) none of these. 4) If an object's mass is decreasing while a constant force is applied to the object, the acceleration A)remains the same. B)decreases. C) increases.

4.14 5) Which has the greater mass? A) an automobile battery B) a king-size pillow C) neither - both have the same 6) A rock is thrown vertically into the air. At the very top of its trajectory the net force on it is A)more than its weight. B)less than its weight. C) its weight.

4.15 7) An object following a straight-line path at constant speed A) has zero acceleration. B) has a net force acting upon it in the direction of motion. C) must be moving in a vacuum or in the absence of air drag. D) has no forces acting on it. E) none of these. 8) A skydiver's terminal velocity will be greatest if she falls A)head first. B) lying flat on her stomach. C) lying flat on her back. D) with her parachute open.

4.16 9) A man weighing 800 N stands at rest on two bathroom scales so that his weight is distributed evenly over both scales. The reading on each scale is A) 200 N. B) 400 N. C) 800 N. D) 1600 N. E) none of these. 10) Whenever the net force on an object is zero, its acceleration A)is zero. B) may be zero.

) An object's weight may properly be expressed in A)newtons. B) meters per second. C) kilograms. D) none of the above. 12) A 10-kilogram block is pushed across a horizontal surface with a horizontal force of 20 N against a friction force of 10 N. The acceleration of the block in meters per second per second is A) 1. B) 2. C) 5. D) 10. E) none of these.

) An object weighs 30 N on Earth. A second object weighs 30 N on the moon. Which has the greater mass? A)they have the same mass B) the one on the moon C) the one on Earth D) not enough information to say 14) When a woman stands at rest with two feet on a scale, the scale reads 500 N. When she gently lifts one foot, the scale reads A)500 N. B)less than 500 N. C) more than 500 N.

) A force is a vector quantity because it has both A) mass and acceleration. B) magnitude and direction. C) action and reaction counterparts. 16) A feather and a coin will have equal accelerations when falling in a vacuum because A) the force of gravity is the same for each in a vacuum. B) the force of gravity does not act in a vacuum. C) their velocities are the same. D) the ratio of each object's weight to its mass is the same. E) none of these.

) A bag of groceries has a mass of 10 kilograms and a weight of about A) 1 N. B) 10 N. C) 100 N. D) 1000 N. E) more than 1000 N.

Answers -- MULTIPLE CHOICE. The one alternative that best completes the statement or answers the question.

4.22 Chapter 4 1) Answer: C 2) Answer: B 3) Answer: B 4) Answer: C 5) Answer: A 6) Answer: C 7) Answer: A 8) Answer: A 9) Answer: B 10) Answer: A 11) Answer: A 12) Answer: A 13) Answer: B 14) Answer: A 15) Answer: B 16) Answer: D 17) Answer: C