MIDTERM STUDY GUIDE—PHYSICS
CONCEPTS
Mathematical Analysis
· Percent error, unit conversions
Kinematics
· Scalar/Vector, distance/displacement, speed/velocity, acceleration, motion graphs, freefall, projectile motion (horizontal/vertical motion independence)
Relative Motion & Vector Addition
· Frames of reference, vector addition in 2-dimensions
Force and Motion
· Nature of force and its affect on motion, Newton’s laws of motion, kinetic & static friction, air resistance
EXAMPLE PROBLEMS
1. A car travels 10.0 km north in 400. s. It then travels 25.0 km south in 850. s. What is the (a) average speed and (b) average velocity of the car?
2. A body with initial speed of 8.0 m/s moves along a straight line with constant acceleration and travels
640. m in 40.0 s. Find the (a) average velocity, (b) final velocity, and (c) acceleration.
3. A truck starts from rest and moves with a constant acceleration of 5.0 m/s². Find its (a) speed and
(b) the distance traveled after 4.0 s has elapsed.
4. A marble dropped from a bridge strikes the water in 5.00 s. Calculate (a) the speed with which it strikes and (b) the height of the bridge.
5. A baseball is thrown straight upward with an initial speed of 30.0 m/s. (a) How long will it rise? (b) How high will it rise? (c) How long after it leaves the hand will it return to the starting point? (d) What is its average velocity for the entire trip?
6. A boat is pointed straight across a river (east) and is moving at a speed of 5.5 m/s relative to the water. The current of the river is south at 3.0 m/s. (a) What is the velocity of the boat relative to the river bank? (b) How long does it take the boat to cross the river if the river is 165 m wide? (c) How far downriver (south) is the boat when it reaches the eastern shore?
7. A force acts on a 2.0 kg mass and gives it an acceleration of 3.0 m/s²north. (a) What acceleration is produced by the same force when acting on a mass of 4.0 kg? (b) What force must be applied to the larger mass in order to produce an acceleration of 3.0 m/s²north?
8. A 500. g chunk of ice sits on the level, horizontal roof of a car. A gust of wind exerts a force of
0.550 N on the ice, causing it to just start to move. (a) What is the coefficient of static friction between the ice and the car? (b) If the coefficient of kinetic friction between the ice and the car is 0.0910, what is the ice’s acceleration if the same 0.550 N force acts once it starts to slide?
9. A 95 kg box is sliding along a level floor with an initial speed of 15 m/s. (a) How large of a constant frictional force is required to stop the box in a distance of 15 m? (b) What is the coefficient of kinetic friction between the box and the floor?
10. A ball rolling with a speed of 20.0 cm/s rolls off the edge of a table that is 80.0 cm high. (a) How long does it take to drop to the floor? (b) How far, horizontally, from the table edge does the ball strike the floor?
11. A body projected upward from level ground at an angle 55º with the horizontal, has an initial speed of
40. m/s. (a) How long does it remain in the air? (b) How far from the starting point will it strike the ground? (c) What is the maximum height the object will reach?
12. Bandit and Stinky are two raccoons that are fighting over a tasty ham bone they found in the trash. The bone has a mass of 1.20 kg and it is sitting on a flat, frictionless surface. Bandit pulls with 24.2 N of force and Stinky pulls in the opposite direction. If the bone accelerates toward Stinky with an acceleration of 0.641 m/s², with what force is Stinky pulling?
13. Make the following unit conversions (look up conversion factors in your book or on-line):
· 0.245 years to minutes • 75.0 m.p.h. to cm/s
· 0.395 gal to cm³ • 15.2 in² to m²
14. Add the following vectors:
· 17.3 m, S and 28.0 m, W • 2.41 m/s, W and 11.4 m/s, N
· 4.9 cm, 41˚N of E and 6.3 cm 12˚S of E • 7.89 m/s, 22˚W of N and 20.9 m/s, 68˚S of E
ANSWERS
1. a. 28.0 m/s b. 12.0 m/s, S
2. a. +16 m/s b. +24 m/s
c. +0.40 m/s²
3. a. 20 m/s b. 40 m
4. a. 49 m/s b. 123 m
5. a 3.06 s b. 45.9 m
c. 6.12 s d. 0 m/s
6. a. 6.3 m/s, 29º S of E
b. 30 s c. 90 m
7. a. +1.5 m/s²,N b. 12 N
8. a. 0.112 b. 0.208 m/s²
9. a. 710 N b. 0.77
10. a. 0.404 s b. 8.08 cm
11. a. 6.7 s b. 150 m
c. 54.8 m
12. 25.0 N
13. 1.29 x 105 min 3.35 x 10³ cm/s
1.50 x 10³ cm³ 9.80 x 10-3 m²
14. 32.9 m, 32˚S of W 11.7 m/s, 78˚N of W
10.0 cm, 11˚N of E 13.0 m/s, 69˚S of E