University:
Jackson College
Course:
PHY 231 | College Physics I
Academic year:

2024
Views:

164

Pages:

10
Author:

Angela Swanson

Name: Key Work, Energy, and Momentum Provincial Exam Questions 1. Is power a scalar or vector quantity, and which are the correct units for measuring it? TYPE OF QUANTITY A. Scalar B Scalar C Vector D. Vector UNITS J/m J/s J/m J/s P= W t Ex not equal 2. A climber's gravitational potential energy increases from 14.000 J to 21 000 J while climbing a cliff. She expends 18 000 J of energy during this activity. What is the efficiency of this process? A. 3% B.39% C. 61% D. 97% Wat 70003 ×100% 18000 3. A 40 000 kg rail car travelling at 2.5m/s collides with and locks to a stationary 30 000 kg car. Determine the speed of the locked cars and state whether the collision is elastic or inelastic. PiP SPEED OF LOCKED CARS TYPE OF COLLISION A 1.4 m/s Elastic B 1.4 m/s Inelastic 4000/3)=100007 C. 1.9 m/s Elastic D. 1.9 m/s Inelastic 4. A 0.25kg cart travelling at 3.0 m/s collides with and sticks to an identical stationary cart on a level track (ignore friction). PP (01512) = (0.5)V v3.0 m/s m=0.25 kg V= 1,5% To what height do the combined carts travel up the hill? Eratt. Epuphio = gh 2 2 h=1.5m (1.5m) = 0.ll m 29 29.8 2 E NS A cyclist must do 1 000 J of work to speed up from 0 m/s to 5.0 m/s. the same cyclist must do 3 000 J of work to speed up from 5.0 m/s to 10.0 m/s (in both instances, friction has 65-0) been ignored). Using principles of physics, explain why more work must be done to speed (100) in this problems than from 0 m/s to 5.0 m/s (remember, friction plays no role V change by 5m, but is squared, so. E chorgro ynore 6. A cyclist increases his kinetic energy from 1 100 J to 5 200 J in 12 s. his power output during this time is PDF = $200-1100 t 123 = 342 Watts = 3.4×10 W 7. Which of the following best represents the momentum of a small car travelling at a city speed limit? ~1000 A. 1000 kg-m/s B. 10 000 kg m/s C. 100 000 kg-m/s D. 1 000 000 kg-m/s P=mv Ih 1000 =1000(50k 36005 = 14000 kgmys closest to lau 8. A 0.080 kg tennis ball travelling east at 15 m/s is struck by a tennis racquet, giving it a velocity if 25 m/s west. What are the magnitude and direction of the impulse given to the ball? imp=4p = m (25m W-150E) = (0.08) (250+1sw) 3.2. N.SW 9. Starting from rest, a farmer pushed a cart 12 m. the graph shows the force F which he applied, plotted against the distance d. F(N) 140 80 0 7 12 d (m) a) How much work did the farmer do moving the cart 12 m? Ayen 1MON-7m+2011-5m b) After the farmer had pushed the 240 kg cart 12 m, it was moving with a velocity of 13805 2.2 m/s. What was the cart's kinetic energy? c) What was the efficiency of this process? E=m² =(2400)(220) =14/10/ 10. Define inelastic collision. Ex is not conserved = 580.875.8×10 c) eff = Wal x1002 580 = 42%