QUESTION IMAGE
Question
test review
- fill in the table.
| name | notation | definition | contact/non contact |
|---|---|---|---|
| normal force | |||
| tension force | |||
| applied force | |||
| frictional force kinetic frictional | |||
| frictional force static frictional | |||
| drag force/air resistance |
- 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?
- 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?
Step1: Recall force - related knowledge
Gravitational force is the force of attraction between two masses. Notation: $F_g$, Definition: $F_g = mg$ (where $m$ is mass and $g$ is gravitational acceleration, $g\approx9.8\ m/s^2$ on Earth), Non - contact force.
Normal force is the force exerted by a surface on an object perpendicular to the surface. Notation: $F_N$, Definition: Counteracts the component of other forces perpendicular to the surface, Contact force.
Tension force is the force transmitted through a string, rope, cable etc. when it is pulled tight. Notation: $F_T$, Definition: Pulling force along the length of a flexible connector, Contact force.
Applied force is a force applied to an object by a person or another object. Notation: $F_{app}$, Definition: A general external force applied, Contact force.
Kinetic frictional force is the force that resists the relative motion of two surfaces in contact. Notation: $F_{k}$, Definition: $F_{k}=\mu_kF_N$ ($\mu_k$ is the coefficient of kinetic friction), Contact force.
Static frictional force is the force that resists the initiation of relative motion between two surfaces in contact. Notation: $F_{s}$, Definition: $0\leq F_{s}\leq\mu_sF_N$ ($\mu_s$ is the coefficient of static friction), Contact force.
Drag force/air resistance is the force that opposes the motion of an object through a fluid (like air). Notation: $F_d$, Definition: Depends on factors like velocity, shape and fluid properties, Contact force.
Step2: Analyze question 2a
A book on a desk is in equilibrium. The force of gravity (weight) $F_g = mg$ acts downwards and the normal force $F_N$ acts upwards. According to Newton's first law for a stationary object, the normal force is equal in magnitude and opposite in direction to the force of gravity. So the force due to gravity (weight) is the same as the normal force in magnitude.
Step3: Calculate normal force in 2b
Given $m = 46\ kg$, using $F_N=mg$ and $g = 9.8\ m/s^2$. Then $F_N=46\times9.8 = 450.8\ N$.
Step4: Analyze question 3a
When holding a backpack by the side, the backpack is in equilibrium. The force of gravity (weight) $F_g = mg$ acts downwards and the tension force in the arm - backpack system (the force you exert to hold it) acts upwards. According to Newton's first law for a stationary object, the force due to gravity (weight) is the same as the tension force in magnitude.
Step5: Calculate tension force in 3b
Given $m = 89\ kg$, using $F_T=mg$ and $g = 9.8\ m/s^2$. Then $F_T=89\times9.8=872.2\ N$.
Snap & solve any problem in the app
Get step-by-step solutions on Sovi AI
Photo-based solutions with guided steps
Explore more problems and detailed explanations
| Name | Notation | Definition | Contact/Non - contact |
|---|---|---|---|
| Normal force | $F_N$ | Counteracts perpendicular component of other forces | Contact |
| Tension force | $F_T$ | Pulling force in a flexible connector | Contact |
| Applied force | $F_{app}$ | General external force | Contact |
| Frictional force Kinetic frictional | $F_{k}$ | $F_{k}=\mu_kF_N$ | Contact |
| Frictional force Static frictional | $F_{s}$ | $0\leq F_{s}\leq\mu_sF_N$ | Contact |
| Drag force/air resistance | $F_d$ | Opposes motion through a fluid | Contact |
2a. The same as
2b. $450.8\ N$
3a. The same as
3b. $872.2\ N$