Unit 4: The Laws of Motion
Section 4.3: Advanced Linear Forces
Question 4.3A: Horizontal
Two forces, ____ x 10 1 N at 15 degrees above the horizon and 175 N at 30 degrees below the horizon are applied to a 2500 kg object in an effort to accelerate it. a) Find the resultant of these two forces. b) Determine angle (magnitude only) of the resultant force from the horizontal. c) What is the acceleration of the object?
Question 4.3B: Horizontal
A 250 N crate is being pushed across a level floor by a force 3____ N at an angle of 30° above the horizontal. The coefficient of kinetic friction between the crate and the floor is 0.24.
What is the acceleration of the box?
Question 4.3C: Horizontal
A clerk moves a box of cans down an aisle by pulling on a strap attached to the box. The clerk pulls with a force of 2____ N at an angle of 25° with the horizontal. The box has a mass of 14 kg and the coefficient of kinetic friction between the box and the floor is 0.480. What is the acceleration of the box?
Questions 4.3D: Horizontal
A hockey puck is hit on a frozen lake and starts moving with a speed of ____ m/s. In 7 s, its speed is 5 m/s. a) What is the puck’s average acceleration? b) What is the average value of the coefficient of kinetic friction between the puck and ice? c) How far does the puck travel?
Question 4.3E: Horizontal
A girl coasts down a hill on a sled, reaching level ground at the bottom with a speed of __.__ m/s. The coefficient of kinetic friction between the sled and the hard, icy snow is 0.060. The girl and the sled together weigh 750 N. How far does the sled travel on the level ground before coming to a rest?

Question 4.3F: Vertical
Consider the 1___ N light fixture supported as in the figure.
Find the tension in the supporting wires.
Question 4.3G: Vertical
An object of mass __.__ kg is suspended on a string from the ceiling of a moving elevator.
Given 9.8 m/s 2 for gravity and the string tension 80 N, find the elevator’s acceleration.
Question 4.3H: Vertical
A student stands on a bathroom scale in an elevator at rest on the 50 th floor of a building.
The scale reads 850 N. As the elevator moves up, the scale reading increases to 9____ N, then decreases back to 850 N. a) Find the acceleration of the elevator. b) As the elevator approaches the 75 th floor the scale reading drops as low as 7____ N.
What is the acceleration of the elevator?
Question 4.3I: Vertical
A person is standing on a spring bathroom scale on the floor of an elevator which is moving up and slowing down at the rate of __.__ m/s 2 . If the person’s mass is 88 kg, what does the scale read?
Question 4.3J: Vertical
An elevator starts from rest with a constant upward acceleration and moves __.__ m in the first 3 s. A passenger in the elevator is holding a 10 kg bundle at the end of a vertical cord.
What is the tension in the cord as the elevator accelerates?
Question 4.3K: Vertical
A descending elevator of mass 200 kg is uniformly decelerated to rest over a distance of __.__ m by a cable in which the tension is 2500 N. Calculate the initial velocity of the elevator at the beginning of the __.__ m descent.