Medgar Evers College City University of New York Department of Physics and Compu

Question

Medgar Evers College City University of New York Department of Physics and Computer Science Physics 20S Final Exam June 10, 2018 Prof. W. Smith- Answer all questions below. Show all work in order to obtain full or partial credit. Be neat. It is prohibited to use a cell-phone or other High-Tech device as a calculator. Cirele the correct answer. 1. Which of the following controls can a. The steering wheel. b the gas pedal. c. the brake pedal. d. all of the be used to make a car sccelerate?() choices a,b & c. e. none of the other choices, 2. When a mass travels in a circle at constant speed, its acceleration (1) a. Is zero because the speed is constant b. points along the are of the cirele c. points away from the circle's center. d. points towards the circle's center 3, which object has the most ?.?.? (1) a. A 2kg ball thrown at 4m/s b. A 4kg ball thrown at v8 m/s c.A 8kg ball thrown at 2 m/s d. None 4. An 80 kg sprinter starts from rest and sprints on a level track, reaching a final speed of 6.5 m/s after 2.5 seconds. His average mechanical power is: b. 89.0 W c. 676W d) 208 W a. 260W 5. A 0.80 kg block traveling at +0.80m/s collides with a 0.60kg ball moving at -0.7 m/s, the collision is inelastic and the blocks are attached after colliding. What is the speed of the system after collision? (1) c. 2.07m/s d) 0.10m/s a 0.75m/s b. 0.16m/s

Explanation / Answer

2. When mass travel in circle at constant speed then only centripital acceleration acting on the object given by which is directed to the center.

Option (d) is correct.

-------

3. KE= 0.5*m*v^2

So all of them have same value of kinetic energy

Option( d) os correct.

--------

4. Workdone= change in kinetic enegy= 0.5 mv^2= 0.5* 80* 6.5^2= 1690 J

Power= workodne /time= 1690/ 2.5= 676 W

Option (c ) is correct.

----------

5. Using conservation of momentum

0.8*0.8+ 0.6*(-0.7) = (0.8+0.6) v

V= 0.16 m/s

Option (b) is correct

---------

Comment in case any doubt..goodluck

Related Questions

Navigate

• Browse (All)
• Browse M
• Subjects

---