chef is trying to get the lid off of a jar that is on really tight. The chef finally uses a rubber square, which she holds over the jar lid to get a better grip and the lid successfully comes off. Which type of friction is this an example of?   1. fluid friction 2. rolling friction 3. sliding friction 4. static friction

(a) If half of the weight of a small 1.00103 kg utility truck is supported by its two drive wheels, what is the magnitude of the maximum acceleration it can achieve on dry concrete? (b) Will a metal cabinet lying on the wooden bed of the truck slip if it accelerates at this rate? (c) Solve both problems assuming the truck has four-wheel drive.

An iron bolt of mass 65.0 g hangs from a string 35.7 cm long. The top end of the string is fixed. Without touching it, a magnet attracts the bolt so that it remains stationary, but is displaced horizontally 28.0 cm to the tight from the previously vertical line of the string. The magnet is located to the right of the bolt and on the same vertical level as the bolt in the final configuration. (a) Draw a free-body diagram of the bolt. (b) Find the tension in the string, (c) Find the magnetic force on the bolt.

As a girl pushes an object across a wood floor, she suddenly comes to an area where the floor has been waxed recently, making it slippery. What becomes true of the coefficient of kinetic friction? A. The coefficient of kinetic friction increases. B. The coefficient of kinetic friction decreases. C. The coefficient of kinetic friction becomes zero. D. The coefficient of kinetic friction becomes negative.

If a horizontal force is applied to an object, how can you tell if an object will start moving? A.The object will start moving if any force is applied. B.The object will start moving if the applied force is greater than the maximum static friction. C.The object will start moving if the applied force is greater than the minimum static friction. D.The object will start moving if the applied force is greater than the maximum kinetic friction. E.The object will start moving if the applied force is greater than the minimum kinetic friction

1. Steve pushes a box across a level floor with a constant horizontal force. This causes the box to move at a constant speed, v. The force from Steve: a. has the same magnitude as the weight of the box. b. equals the sum of the box's weight and the total frictional forces opposing the box's motion. c. has the same magnitude as the frictional forces opposing the box's motion. d. has greater magnitude than the frictional forces opposing the box's motion. e. has greater magnitude than the weight of the box. 2. Steve now doubles the force he applies to th box from the previous problem. Which of the following is true? a. The box will move at double the previous speed. b. The box will move with a continuously increasing speed. c. The box will increase speed for a while, then move at a constant speed. d. The box will continue to move at the same speed for a while, then continually increase speed. e. The box will move at a greater constant speed, but not necessarily double the speed.

A box is pulled at a constant speed, v, along a horizontal surface with a kinetic coefficient of friction less than 1. The person pulls with a constant horizontal force, F, on the box. The constant horizontal force the person pulls with: A. Has the same size as the weight of the box. B. Is greater than the weight of the box. C. Is less than the weight of the box. D. Is greater than the friction force.

1. A child stands on a bathroom scale while riding in an elevator. The child's weight when the elevator is not moving is 490 N. What does the scale read when the elevator accelerates upward at 1.3 m/s^2?a. 490 N b. 555 N c. 65 N d. 425 N   2. The force that one surface exerts on another when the two rub against each other is called _____. a. gravity b. inertia. c. friction. d. acceleration.   answer only

What causes the force that moves a boat forward when someone rows it?  a. The force is caused by the rower’s arms. b. The force is caused by an interaction between the oars and gravity.  c. The force is caused by an interaction between the oars and the water the boat is traveling in.  d. The force is caused by friction.

Which type(s) of friction is proportional to the normal force between two surfaces? Select one: a. Static friction. b. Static and kinetic friction. c. Not any types of friction. d. Kinetic friction.