Exam 1: A: Foundations

A 1.10-kg wrench is acting on a nut trying to turn it. The length of the wrench lies directly to the east of the nut. A force 150.0 N acts on the wrench at a position 15.0 cm from the center of the nut in a direction 30.0° north of east. What is the magnitude of the torque about the center of the nut?

You are standing on a skateboard,initially at rest.A friend throws a very heavy ball towards you.You can either catch the object or deflect the object back towards your friend (such that it moves away from you with the same speed as it was originally thrown).What should you do in order to MINIMIZE your speed on the skateboard?

A packing crate rests on a horizontal surface.It is acted on by three horizontal forces: 600 N to the left,200 N to the right,and friction.The weight of the crate is 400 N.If the 600-N force is removed,the resultant force acting on the crate is

Two cables of the same length are made of the same material,except that one cable has twice the diameter of the other cable.When the same potential difference is maintained across both cables,which of the following statements are true? (There may be more than one correct choice.)

A uniform disk has a mass of 3.7 kg and a radius of 0.40 m.The disk is mounted on frictionless bearings and is used as a turntable.The turntable is initially rotating at 30 rpm.A thin-walled hollow cylinder has the same mass and radius as the disk. It is released from rest,just above the turntable,and on the same vertical axis.The hollow cylinder slips on the turntable for 0.20 s until it acquires the same final angular velocity as the turntable.What is the final angular momentum of the system?

Each plate of an air-filled parallel-plate air capacitor has an area of 0.0040 m²,and the separation of the plates is 0.080 mm.An electric field of 5.3 × 10⁶ V/m is present between the plates.What is the energy density between the plates? (ε₀ = 8.85 × 10^-12 C²/N • m²)

A monkey is sitting at the top of a tree 20 m above ground level.A person standing on the ground wants to feed the monkey.He uses a bow and arrow to launch the food to the monkey.If the person knows that the monkey is going to drop from the tree at the same instant that the person launches the food,how should the person aim the arrow containing the food? Air resistance is small enough to be ignored.

A light beam from a 2.1-mW He-Ne laser has a wavelength of 633 nm.How many photons does the laser emit in one second? (h = 6.626 × 10^-34 J • s,c = 3.00 × 10⁸ m/s)

A slit of width 0.010 mm has light of frequency 5.0 × 10¹⁴ Hz passing through it onto a screen 60 cm away.How wide is the central maximum? (c = 3.00 × 10⁸ m/s)

Two identical stones are dropped from rest and feel no air resistance as they fall.Stone A is dropped from height h,and stone B is dropped from height 2h.If stone A takes time t to reach the ground,stone B will take time

A turntable has a radius of 0.80 m and a moment of inertia of 2.0 kg • m².The turntable is rotating with an angular velocity of 1.5 rad/s about a vertical axis though its center on frictionless bearings.A very small 0.40-kg ball is projected horizontally toward the turntable axis with a velocity of 3.0 m/s.The ball is caught by a very small and very light cup-shaped mechanism on the rim of the turntable (see figure).The percent of the initial kinetic energy of the system that is lost during the capture of the ball is closest to

Which statements are true for an electron moving in the direction of an electric field? (There may be more than one correct choice.)

A rescue plane flying horizontally at 72.6 m/s spots a survivor in the ocean 182 m directly below and releases an emergency kit with a parachute.Because of the shape of the parachute,it experiences insignificant horizontal air resistance.If the kit descends with a constant vertical acceleration of 5.82 m/s²,how far away from the survivor will it hit the waves?

When two point charges are a distance d part,the electric force that each one feels from the other has magnitude F.In order to make this force twice as strong,the distance would have to be changed to

A plate falls vertically to the floor and breaks up into three pieces,which slide along the floor.Immediately after the impact,a 320-g piece moves along the x-axis with a speed of 2.00 m/s and a 355-g piece moves along the y-axis with a speed of 1.50 m/s.The third piece has a mass of 100 g.In what direction does the third piece move? You can neglect any horizontal forces during the crash.

A thin converging lens is found to form an image of a distant building 24 cm from the lens.If an insect is now placed 16 cm from this lens,how far FROM THE INSECT will its image be formed?

The figure shows a 100-kg block being released from rest from a height of 1.0 m.It then takes it 0.90 s to reach the floor.What is the mass m of the other block? The pulley has no appreciable mass or friction.

An extremely light rod 1.00 m long has a 2.00-kg mass attached to one end and a 3.00-kg mass attached to the other. The system rotates at a constant angular speed about a fixed axis perpendicular to the rod that passes through the rod 30.0 cm from the end with the 3.00-kg mass attached. The kinetic energy of the system is measured to be 100.0 J. (a)What is the moment of inertia of this system about the fixed axis? (b)What is the angular speed (in revolutions per second)of this system?

An airplane flies 120 km at a constant altitude in a direction 30.0° north of east. A wind is blowing that results in a net horizontal force on the plane due to the air of 2.40 kN in a direction 10.0° south of west. How much work is done on the plane by the air?

A level pipe contains a nonviscous,incompressible fluid with a density 1200 kg/m³ that is flowing steadily. At one position within the pipe,the pressure is 300 kPa and the speed of the flow is 20.0 m/s. At another position,the pressure is 200 kPa. What is the speed of the flow at this second position?