Question

1 fill in the table

name	notation	definition	contact/non - contact
normal force	$f_n$	perpendicular component of applied forces	contact
tension force	$f_t$	pulling force in a connector	contact
applied force	$f_{app}$	external force	contact
frictional force kinetic frictional	$f_k$	$f_k=mu_kf_n$	contact
frictional force static frictional	$f_s$		contact
drag force/air resistance	$f_d$	opposes motion through a fluid	contact

1. a book is sitting on a desk.

a. the force due to gravity (weight) is (the same as/different from) the normal force. (circle one.)
b. if the object has a mass of 46 kg, what is the normal force of the object?

1. you are holding your backpack by your side.

a. the force due to gravity (weight) is (the same as/different from) the tension force. (circle one.)
b. if the object has a mass of 89 kg, what is the tension force of the object?

Explanation:

Step1: Analyze forces on book on desk (part a)

The book is at rest. According to Newton's first - law, the net force on it is zero. The gravitational force ($F_g = mg$) acts downwards and the normal force ($F_N$) acts upwards. So the force due to gravity (weight) is the same as the normal force in magnitude but opposite in direction.

Step2: Calculate normal force on book (part b)

Use the formula $F_N=mg$. Given $m = 46$ kg and $g = 9.8$ m/s². Then $F_N=46\times9.8 = 450.8$ N.

Step3: Analyze forces on backpack (part a)

The backpack is at rest. The gravitational force ($F_g = mg$) acts downwards and the tension force ($F_T$) in the arm - holding it acts upwards. So the force due to gravity (weight) is the same as the tension force in magnitude but opposite in direction.

Step4: Calculate tension force on backpack (part b)

Use the formula $F_T=mg$. Given $m = 89$ kg and $g = 9.8$ m/s². Then $F_T=89\times9.8=872.2$ N.

Answer:

1. a. the same as

b. 450.8 N

1. a. the same as

b. 872.2 N