Chapter 4: Physics
An object is at rest on an incline. The component of gravity acting downward and along the incline on the object is described as Fg, x = +8.0 N. Which axis is pointing up the incline?
-x-axis
Two books are lying next to each other on a library table. The force due to gravity on the first book is 9 N and on the second is 13 N. The gravitational force on the table itself is 125 N. The floor supports the table with an upward force of 147 N. In a free-body diagram of the table, how many contact forces and how many field forces should be represented?
3,1
The normal force
Acts perpendicular to a surface.
The acceleration due to gravity
All of the above
Two forces act on an object. The magnitude of the net force acting on the object
Cannot be determined from the given information.
A lubricant decreases kinetic friction between surfaces. The most likely reason it reduces kinetic friction is because the lubricant
Changes the composition and qualities of the surfaces in contact.
For an object in contact with a given surface, the kinetic friction acting on the object
Depends on the composition and qualities of the surfaces in contact.
The coefficient of kinetic friction
Depends on the composition and qualities of the surfaces in contact.
Units that measure weight are units of
Force
The change in the horizontal velocity of a 12-kg scooter is +0.5 m/s. What is the net horizontal force acting on it?
Greater than 0 N
Which of the following statements describe free-body diagrams?
I and II
Which of the following statements are true about the concept of field forces?
I, II, and III
Which of the following statements describe force diagrams?
I, II, and III
Which of the following statements are true about Fs, maxin the equation µs = Fsmax/ Fn
II and III
A truck and a car uniformly accelerate from rest to a velocity of 3.0 m/s in equal time intervals. The truck is ten times as massive as the car. Which of the following statements is correct?
The force on the truck is 10 times the force on the car.
The gravitational force exerted on an object would most likely be represented by which force vector?
↓
All of the following statements about kinetic friction are true except
For an object on an incline, kinetic friction increases as the angle of the incline above the horizontal increases.
An action exerted on an object which may change the object's state of rest or motion defines
Force
Which of the following statements describe an object in equilibrium?
I, II, and III
Which of the following is true of inertia?
It is described in Newton's first law of motion.
A batter strikes a baseball with a bat. Identify an action-reaction pair and describe the forces exerted by each.
The batter exerts a force on the bat; the bat exerts a force on the batter.
A force of 5 N and a force of 15 N acting on an object can produce the following net forces except
5 N
During a three-part circus stunt, a clown holds a ball. The clown then tosses the ball upward. After releasing it, the ball is caught a few moments later from above by another clown on a trapeze. Which set of data could represent the normal force exerted by the ground on the first clown during the stunt? The force due to gravity on the clown is 680 N and that on the ball is 20 N.
700 N, 705 N, 680 N
A force unit is defined as the product of a mass unit and a unit of
Acceleration
In an action-reaction pair, the
Action force and the reaction force act on two different objects.
Which of the following situations describes inertia?
All of the above
In interactions of action-reaction pairs involving Earth and everyday objects, the effect on Earth's motion is often negligible because
Earth has great inertia.
A plank is inclined at angle , north of west. The direction of the normal force exerted by that plank on an object would be oriented at angle ,
East of north
A student holds a 6-N block of wood from a spring balance in an express elevator that maintains constant velocity traveling between floors. A spring scale reading of 5.9 N indicates that the elevator is
Ending an ascending trip
Two dogs are tugging on a toy. One dog pulls with a horizontal force of 14 N due north. The other is pulling due east with a horizontal force of 14 N. What is the direction of the net external horizontal force on the toy?
Northeast
In which situation is the net force acting on a car zero?
The car maintains both its speed and direction.
A single force acting on an object is represented in a free-body diagram of the object by the following force vector:↑ Which of the following force vectors represents a single force acting on the object that will bring the object into equilibrium?
↓