A pen contains a spring with a spring constant of 208 N/m. When the tip of the pen is in its retracted position, the spring is compressed 5.60 mm from its unstrained length. In order to push the tip out and lock it into its writing position, the spring must be compressed an additional 6.90 mm. How much work is done by the spring force to ready the pen for writing? Be sure to include the proper algebraic sign with your answer.

1. What is the weight of a 87.4 kg object? w=?

2.What was the average speed in km/h of a car that travels 798 km in 6.1h?

3. What net force is needed to give a 22 kg grocery cart an acceleration of 2.3 m/s² ?

4.Suppose a radio signal travels from Earth and through space at a speed of 3.0 × 10⁸ m/s. How far into space did the signal travel during the first 38.7 minutes?

5. How far away was a lightning strike if thunder is heard 5.23 seconds after seeing the flash? Assume that sound traveled at 350.0 m/s during the storm.

6.What is the acceleration of a car that moves from rest to 19.1 m/s in 10.0 s?

7. How long will be required for a car to go from a speed of 15.6 m/s to a speed of 26.7 m/s if the acceleration is 3.0 m/s²?

Ref: Yang

A box with mass m is dragged across a level floor having a coefficient of kinetic friction ?k by a rope that is pulled upward at an angle ? above the horizontal with a force of magnitude F.

Part A

In terms of m, ?k, ?, and g, obtain an expression for the magnitude of force required to move the box with constant speed.

Part B

Knowing that you are studying physics, a CPR instructor asks you how much force it would take to slide a 90-kg patient across a floor at constant speed by pulling on him at an angle of 25? above the horizontal. By dragging some weights wrapped in an old pair of pants down the hall with a spring balance, you find that ?k=0.35. Use the result of part A to answer the instructor's question.

Explain the relationship Fb = PVg

A block of mass m1 = 2.00kg and a block of mass m2 = 6.00kg are connected by a mass less string over a pulley in a shape of a solid disk having radius radius R=0.250m and mass M = 10.0kg. The fixed wedgede shaped ramp makes a angle of theta = 30.0 degrees. The coefficient of kinetic friction is 0.360 for both blocks. (a) draw diagram(b) acceleration of the two blocks(c) tension of both sides.

1.  A rectangular loop of wire (0.2 m wide and 0.3 m tall) carrying a current of 0.6 A is in the xy plane, with its right edge along the +y axis. A magnetic field (uniform, B = 1.2 T) exists along a direction that is 74° from the +z axis in the xz plane. What magnitude of torque will act on the loop of wire at that moment ? a) 0.42 Nm b)0.15 Nm c) 0.04 Nm d) 0.09 Nm

2. If the B-field in the previous problem was oriented at 50° from +x in the xz plane determine the magnitude and direction of the torque on a 150 turn loop of the same size as the coil in question#1. a) 4.2 Nm, along +y b) 2.8 Nm, along +y c) 1.1 Nm, along +z d) 0.5 Nm, along +z

3. Will the plane of the coil of wire in question #2 initially swing toward the +z or the -z axis? a) +z b) -z c) Neither +z nor -z

4. For the torque on a current carrying loop to be maximized, the angle between the normal to the plane of the loop and the B-field must be: a) zero. b)45°. c) 90° d) 180°

A long piece of wire with a mass of 0.170 kg and total length of 4.00 m is used to make a square coil with a side of 0.100 m. The coil is hinged along a horizontal side, carries a 3.20 A current, and is placed in a vertical magnetic field with a magnitude of 0.0100 T.

Two 2.0 cm -diameter disks face each other, 3.0 mm apart. They are charged to ±11nC.

Part A

What is the electric field strength between the disks?

Part B

A proton is shot from the negative disk toward the positive disk. What launch speed must the proton have to just barely reach the positive disk?

Investigation B, The Braun Electroscope

       The Braun electroscope consists of a metal disc at the upper end of a metal rod insulated from the case of the instrument. The rod supports a light metal vane free to rotate about a horizontal axis. When the electroscope is charged the vane swings from its normal vertical position to a near equilibrium position. The angle it makes with the vertical is proportional to the charge of the electroscope.

1            A. Ground the electroscope by touching the disc.

B. Bring a negatively charged rod near the disc of the electroscope.

C. Remove the rod.

2            A. Ground the electroscope.

B. Bring a negatively charged rod near the disc of the electroscope.

C. Touch the rod to the disc. This is charging by contact.

D. Remove the rod.

3   A. Charge the electroscope as in 7, by contact.

B. Bring the negatively charged rod to within 5 cm. of the disc of the electroscope.

C. Bring the negatively charged rod as close to the disc as possible without a spark jumping from the rod to the disc.

D. Remove the rod.

4   A. Charge the electroscope as in 7, by contact.

B. Bring a positively charged rod to within about 5cm. of the disc of the electroscope.

C. Bring a positively charged rod as close to the disc of the electroscope as possible without a spark jumping from the rod

D. Remove the rod.

5     A. Ground the electroscope.

      B. Bring a negatively charged rod near the disc of the electroscope.

      C. keeping the rod near the disc, ground the telescope.

      D. Keeping the rod near the disc, removes the grounding connection.

      E. Remove the rod. The electroscope has been charged by induction.

6     A. Charge the electroscope by induction as 10 observing carefully the charging distance between rod and disc when the electroscope is grounded.

B. Bring a negatively charged rod near the disc. Draw diagrams for the following cases:

1) Rod beyond the charging distance.

2) Rod at charging distance.

3) Rod inside the charging distance.

C. Remove the rod.

7      A. Charge the electroscope by induction as in 10.

       B. Bring a positively charged rod near the electroscope.

       C. Remove the rod.

Note: the experiments above might be repeated, replacing a positive with a negative rod and a negative with a positive rod. In all cases the charge distribution would be opposite to that for the above experiments.

8. Charge the electroscope positively by induction. Record the electroscope positively by induction. Record the effect of bringing the hand near the knob of the electroscope.

Charge the electroscope negatively by induction. Record the effect of bringing the hand near the electroscope. Diagrams need not be drawn for this part.

I have no idea about this lab report!!~
The prof reuqire us to explain which situation !~~ Please help

Consider an object sliding down a frictionless incline.

1. Would you expect the object to move at a constant velocity or would you expect the object to accelerate as it moves down the incline?

2. If the angle of inclination increased, would you expect your answer to the previous question to change? If not, why not? If so, why and how?

3. How could you experimentally show that the velocity changed as the object slid down the incline? What measurements would you have to make and how could you make them?

A student, while moving out of his old apartment, is loading a rented moving truck using a ramp which is at a rather steep angle of 28.0 degrees above the horizontal; the ramp is 2.70 m long. At one point in the loading process he drags a loaded suitcase of mass 25.50 kg up the full length of the ramp. The wheels on the old suitcase have long since ceased to function properly, so that the effective coefficient of kinetic friction between the suitcase and the inclined ramp is 0.260. The old suitcase has a strap attached to one corner, and the student does the dragging by pulling on this strap and running up the ramp (he is in a hurry) so that he and the suitcase speed up while going up the ramp. It turns out the the student is able to maintain a tension of 188.0 N during his pull, and the angle between the strap and the incline is 19.0 degrees(the strap direction is 19.0 degrees higher than the incline angle).

A.How much work is done on the suitcase by the tension force during the pull up the ramp?

B.How much work is done by the force of gravity on the suitcase by the Earth during the pull up the ramp?

D.How much work is done by the frictional force on the suitcase by the ramp during the pull up the ramp?

E.As a result of the pull up the incline, what is the increase in the thermal energy present in the suitcase and in the surface of the ramp?

F.What is the change in the kinetic energy of the suitcase as a result of the pull up the incline?

The total electric field consists of the vector sum of two parts. One part has a magnitude of E1 = 1000 N/C and points at an angle θ1 = 35o above the +x axis. The other part has a magnitude of E2 = 2000 N/C and points at an angle θ2 = 55o above the +x axis. Find the magnitude and direction of the total field. Specify the directional angle relative to the x axis.

1. Determine the quantity of charge on the following questions. Use 1.60 x 10-19 C for the charge of an electron. [3 marks]

a. a plastic tube which has been rubbed with animal fur and gained 3.8x109 electrons.

b. a vinyl balloon which has been rubbed with animal fur and gained 1.7x1012 electrons.

c. an acetate strip which has been rubbed with wool and lost 7.3x108 electrons.

A uranium nucleus 238U may stay in one piece for billions of years, but sooner or later it decays into a particle of mass 6.64 X 10^27 kg and 234 Th nucleus of mass 3.88 X 10^-25 kg. and the decay process itself is extremely fast (it takes about 10^-2O s). Suppose the uranium nucleus was at rest just before the decay. If the a particle is emitted at a speed of 5.94 X10^6 m/s,

what would be the recoil speed of the thorium nucleus? Answer in units of m/ s