Physics 201 MWF10:20 Fall 2004 (Ford)

Exam II Chapts. 5-7 in Cutnell and Johnson 6th ed


Show all your work. Partial credit will be given if earned. Write your answers in the blanks provided.

(16 pts) 1. A ball is thrown with a speed of 20 m/s at an angle of 53° above the horizontal. What is the speed of the ball when it is a vertical distance of 12.0 m above the point where it was released by the thrower? Neglect air resistance.



Ans. ___12.8 m/s____


(22 pts) 2. A small rock is tied to a string and set in motion in a horizontal circle with constant speed. The string is 8.0 m long and makes a constant angle of 37° with the vertical. If the tension in the string is 5.6 N, what is



a) the mass m of the rock?

Ans. ____0.457 kg___

b) the time for the rock to complete one revolution?

Ans. ____5.08 s____


(20 pts) 3. A fireworks rocket with mass 8.0 kg is moving horizontally due east at 22.0 m/s when it explodes and breaks into two pieces of 4.0 kg each. Immediately after the explosion one piece is traveling horizontally at 25.0 m/s in the direction 53° north of east. What are the magnitude v_f and direction of the other piece immediately after the explosion?



Ans. v_f ___35.2 m/s____

____34.6°_____


(20 pts) 4. A cart of mass 30 kg is sliding to the left on horizontal frictionless tracks and has an initial speed of 5.0 m/s. A package of mass 6.0 kg slides down a chute that is inclined at 37° below the horizontal. The end of the chute is a vertical distance of 12.0 m above the bottom of the cart. The package has a speed of 8.0 m/s as it leaves the end of the chute. The package lands in the cart. After the package has come to rest relative to the cart, what is the velocity (magnitude and direction) of the cart?



Ans. magnitude ____3.1 m/s_____

direction ___to the left____


(22 pts) 5. A small block of mass 0.050 kg slides on the inside of a circular track that has radius 2.0 m. At point A at the bottom of the circle the block has speed 14.0 m/s. As the block slides through point B at the top of the circle, the track exerts a downward normal force of 1.2 N on the block.



a) What is the speed of the block at point B?

Ans. _____8.22 m/s___

b) What amount of work is done on the block by friction as the block slides from point A to point B?

Ans. __-1.25 J_____