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Ch 05: Applying Newton's Laws
Young & Freedman Calc - University Physics 14th Edition
Young & Freedman Calc14th EditionUniversity PhysicsISBN: 9780321973610당신이 사용하는 게 아니라요?교과서 변경
5장, 문제 32

A pickup truck is carrying a toolbox, but the rear gate of the truck is missing. The toolbox will slide out if it is set moving. The coefficients of kinetic friction and static friction between the box and the level bed of the truck are 0.3550.355 and 0.6500.650, respectively. Starting from rest, what is the shortest time this truck could accelerate uniformly to 30.030.0 m/s without causing the box to slide? Draw a free-body diagram of the toolbox.

검증된 단계별 안내
1
Step 1: Begin by analyzing the forces acting on the toolbox. Draw a free-body diagram of the toolbox. The forces include: (1) the gravitational force acting downward, \( F_g = m g \), (2) the normal force acting upward, \( F_N \), and (3) the frictional force acting horizontally, which prevents the toolbox from sliding. The frictional force is determined by the static friction coefficient \( \mu_s \).
Step 2: Use Newton's second law to analyze the horizontal forces. The maximum static friction force \( F_{f, \text{max}} \) is given by \( F_{f, \text{max}} = \mu_s F_N \). Since the toolbox is not sliding, the normal force \( F_N \) equals the gravitational force \( F_g \), so \( F_{f, \text{max}} = \mu_s m g \).
Step 3: Relate the frictional force to the acceleration of the truck. The toolbox will remain stationary relative to the truck as long as the acceleration \( a \) does not exceed the maximum static friction force divided by the mass of the toolbox. Using \( F = ma \), the maximum acceleration is \( a_{\text{max}} = \frac{F_{f, \text{max}}}{m} = \mu_s g \).
Step 4: Calculate the shortest time required for the truck to accelerate uniformly to 30.0 m/s without causing the toolbox to slide. Use the kinematic equation \( v = a t \), where \( v \) is the final velocity, \( a \) is the acceleration, and \( t \) is the time. Rearrange to solve for \( t \): \( t = \frac{v}{a} \). Substitute \( a_{\text{max}} = \mu_s g \) into the equation.
Step 5: Substitute the known values into the equations. Use \( \mu_s = 0.650 \), \( g = 9.8 \, \text{m/s}^2 \), and \( v = 30.0 \, \text{m/s} \) to calculate the time \( t \). This will give the shortest time the truck can accelerate uniformly to 30.0 m/s without causing the toolbox to slide.

비슷한 문제에 대한 검증된 영상 답변:

이 영상 해법은 위 문제에 도움이 된다고 튜터들이 추천한 것입니다.
영상 길이:
4m

주요 개념

질문에 올바르게 답하기 위해 반드시 이해해야 하는 핵심 개념들은 다음과 같습니다.

Friction

Friction is the force that opposes the relative motion of two surfaces in contact. It is characterized by two coefficients: static friction, which prevents motion until a certain threshold is reached, and kinetic friction, which acts when surfaces are sliding past each other. In this scenario, the static friction coefficient (0.650) is crucial for determining the maximum acceleration the truck can have without the toolbox sliding.
추천 영상:
가이드 코스
08:11
Static Friction & Equilibrium

Newton's Second Law of Motion

Newton's Second Law states that the acceleration of an object is directly proportional to the net force acting on it and inversely proportional to its mass (F = ma). This principle is essential for calculating the forces acting on the toolbox and determining the maximum acceleration the truck can achieve without exceeding the static friction limit.
추천 영상:
가이드 코스
06:54
Intro to Forces & Newton's Second Law

Free-Body Diagram

A free-body diagram is a graphical representation that shows all the forces acting on an object. In this case, it would illustrate the gravitational force acting downward on the toolbox, the normal force acting upward, and the frictional force opposing the motion. This diagram is vital for visualizing the forces involved and applying Newton's laws to solve for the truck's acceleration.
추천 영상:
가이드 코스
08:42
Free-Body Diagrams
관련 실천
교과서 질문

Two crates connected by a rope lie on a horizontal surface (Fig. E5.375.37). Crate A has mass mAm_A, and crate B has mass mBm_B. The coefficient of kinetic friction between each crate and the surface is μkμ_k. The crates are pulled to the right at constant velocity by a horizontal force FF. Draw one or more free-body diagrams to calculate the following in terms of mAm_A, mBm_B, and μkμ_k: the tension in the rope connecting the blocks.

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교과서 질문

Two crates connected by a rope lie on a horizontal surface (Fig. E5.375.37). Crate A has mass mAm_A, and crate B has mass mBm_B. The coefficient of kinetic friction between each crate and the surface is μkμ_k. The crates are pulled to the right at constant velocity by a horizontal force FF. Draw one or more free-body diagrams to calculate the following in terms of mAm_A, mBm_B, and μkμ_k: the magnitude of FF.

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교과서 질문

A 45.045.0-kg crate of tools rests on a horizontal floor. You exert a gradually increasing horizontal push on it, and the crate just begins to move when your force exceeds 313313 N. Then you must reduce your push to 208208 N to keep it moving at a steady 25.025.0 cm/s. Suppose you were performing the same experiment on the moon, where the acceleration due to gravity is 1.621.62 m/s2.

(i) What magnitude push would cause it to move?

(ii) What would its acceleration be if you maintained the push in part (b)? Note: Part (b) asked what push you must exert to give it an acceleration of 1.101.10 m/s2.

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교과서 질문

A 25.025.0-kg box of textbooks rests on a loading ramp that makes an angle αα with the horizontal. The coefficient of kinetic friction is 0.250.25, and the coefficient of static friction is 0.350.35. At this angle, find the acceleration once the box has begun to move.

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교과서 질문

A 45.045.0-kg crate of tools rests on a horizontal floor. You exert a gradually increasing horizontal push on it, and the crate just begins to move when your force exceeds 313313 N. Then you must reduce your push to 208208 N to keep it moving at a steady 25.025.0 cm/s. What push must you exert to give it an acceleration of 1.101.10 m/s2?

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views
2
rank
교과서 질문

A 45.045.0-kg crate of tools rests on a horizontal floor. You exert a gradually increasing horizontal push on it, and the crate just begins to move when your force exceeds 313313 N. Then you must reduce your push to 208208 N to keep it moving at a steady 25.025.0 cm/s. What are the coefficients of static and kinetic friction between the crate and the floor?

3347
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