Lecture 1 Chapter 1: Gravitational Forces and Acceleration

What is the direction of the acceleration aR of a mass on the surface of the earth?

Perpendicular to the earth's surface
Away from the center of the earth
Parallel to the earth's surface
Toward the center of the earth (correct)

What is the value of acceleration due to gravity on the surface of the earth?

10 ms-2
9.5 ms-2
9.8 ms-2 (correct)
9.2 ms-2

What is the force acting on a mass at the surface of the earth?

FG only
FG + w
w only
FG - w (correct)

Where is the value of g equal to GME/R2?

At the poles (C) Signup and view all the answers

What is the effect of the earth's rotation on the weight of an object?

It decreases the weight (C) Signup and view all the answers

What is the expression for the acceleration due to gravity on the earth's surface?

GMe/R2 (D) Signup and view all the answers

What is the magnitude of the resistive force expressed as?

1/R = DAρv^2/2 (C) Signup and view all the answers

What is the value of the drag coefficient for spherical objects?

0.5 (A) Signup and view all the answers

What is the net force acting on an object released from rest?

Fg - R (A) Signup and view all the answers

What is the acceleration of the object when it reaches terminal speed?

0 (B) Signup and view all the answers

What is the terminal velocity of a spherical water droplet with a radius of 5 microns in still air?

3 × 10^(-3) m/s (B) Signup and view all the answers

What is the direction of the actual direction at other locations with respect to the earth's axis of rotation?

Perpendicular to the earth's axis of rotation at the given latitude (C) Signup and view all the answers

What is the dynamic viscosity of air at 20°C?

1.8 × 10^(-5) kg/m · s (D) Signup and view all the answers

What is the terminal speed of an object in terms of its mass and other parameters?

v_T = sqrt(2mg/ρDA) (A) Signup and view all the answers

Why does the baseball strike the ground first in the quiz?

Because it has a smaller cross-sectional area (C) Signup and view all the answers

What is the value of g in m/s2, approximately, according to the calculation?

0.0337 (D) Signup and view all the answers

What is the density of water in kg/m³?

1000 kg/m³ (B) Signup and view all the answers

What is the period of the rotation of the earth in seconds?

8.64 × 10^4 s (B) Signup and view all the answers

What is the time at which the sphere reaches a speed of 0.900 vT?

11.7 ms (C) Signup and view all the answers

What is the model of resistive force applicable to objects moving at high speeds through air?

Resistive force proportional to object speed squared (D) Signup and view all the answers

In which situation is the resistive force assumed to be proportional to the speed of the moving object?

For objects falling slowly through a liquid and for very small objects, such as dust particles, moving through air (C) Signup and view all the answers

What is the radius of the spherical water droplet in the example?

5 microns (C) Signup and view all the answers

What is the expression for the resistive force, R, if it is proportional to the object's velocity?

R = -bv (C) Signup and view all the answers

What is the dependence of the resistive force on the speed of the moving object for large objects, such as a skydiver moving through air?

It is proportional to the square of the speed of the moving object (D) Signup and view all the answers

A baseball is thrown with a speed of 40.2 m/s. What is the primary factor that affects the resistive force acting on the ball?

Cross-sectional area of the ball (B) Signup and view all the answers

What is the terminal velocity of a 75 kg skydiver descending head first with a cross-sectional area of approximately 0.18m²?

350km/h (C) Signup and view all the answers

What is the Resistive force acting on a 0.145-kg baseball thrown at 40.2 m/s?

1.2 N (D) Signup and view all the answers

What is the primary purpose of finding the terminal velocity of an object?

To determine the resistive force acting on the object (C) Signup and view all the answers

What is the unit of the drag coefficient?

Unitless (C) Signup and view all the answers

What is the relation between the resistive force and the speed of an object?

The resistive force is proportional to the square of the speed of the object (A) Signup and view all the answers