PHYS 3 PROBSET 1

1st Semester, AY 2013-2014

1. Alex went for a walk one day. He walked north 6.0 km at 6.0 km/h and then west 10 km at 5.0 km/hr. Determine

a.)the total distance of the entire trip, b.)the total displacement of the entire trip, c.)the average speed of the entire

trip, d.)the average velocity of the entire trip, and e.) the average acceleration of the entire trip.

2. A physics professor leaves her house and walks along the sidewalk toward campus. After 5 min it starts to rain and

she returns home. Her distance from her house as a function of time is shown in the figure. At which of the labeled

points is her velocity (a) zero? (b) constant and positive? (c) constant and negative? (d) increasing in magnitude?

(e) decreasing in magnitude?

3. Add the following vectors :( R=A+B+C+D)

A = 3m, 60o East of North B = 20m, 286o North of West

C = 19m, 32o South of East D = 86m, 115o North of East.

4. The driver of a car slams on the brakes when he sees a tree blocking the road. The car slows uniformly with an

acceleration of -5.60 m/s2 for 4.20 s, making straight skid marks 62.4 m long ending at the tree. With what speed

does the car then strike the tree?

5. A robot probe drops a camera off the rim of a 239 m high cliff on Mars, where the free-fall acceleration is 3.7

m/s2. a.) Find the time required for the camera to reach the ground. b.) Find the velocity with which it hits the

ground.

6. If Lebron James has a vertical leap of 1.29 m, what is his take-off speed? And what is his hang time (total time to

move upwards to the peak and then return to the ground)?

7. If a plane is flying in a horizontal path y meter above the ground with a speed of v m/s, at what distance from the

target should the pilot release the canister to hit the target. (g = 9.8 m/s2).

8. A daring 510-N swimmer dives off a cliff with a running horizontal leap. What must her minimum speed be just as

she leaves the top of the cliff so that she will miss the ledge at the bottom, which is 1.75m wide and 9.00m below

the top of the cliff?

9. A man stands on the roof of a building that is 30.0 m tall and throws a rock with a velocity of magnitude 40.0 m/s

at an angle of 33.0 degrees above the horizontal. Air resistance is neglected. Calculate the horizontal distance from

the base of the building to the point where the rock strikes the ground.

10. A basketball player is fouled and knocked to the floor during a layup attempt. The player is awarded two free

throws. The center of the basket is a horizontal distance of 4.21 m from the foul line and is a height of 3.05m above

the floor. On the first free throw attempt, the player shoots the ball at the center of the basket. The ball is released

at 35 degrees above the horizontal and 1.83 m above the floor. You can ignore air resistance. What initial speed does

the player gives the ball?

11. Suppose A = BC, where A has the dimension L/M and C has the dimension L/T. Then what is the dimension of B?

12. A swimmer heads directly across a river swimming at 1.6 m/s relative to still water. She arrives at a point 40 m

downstream from the point directly across the river, which is 80 m wide. Determine a.) the speed of the current,

b.)the magnitude of the swimmer's resultant velocity, c.) the direction of the swimmer's resultant velocity, and

d.)the time it takes the swimmer to cross the river.

13. Papa bear whirls a ball on a sling in a horizontal circle of radius 1m. How many revolutions per minute must the

ball make if its acceleration toward the center of the circle is to have the same magnitude as the acceleration due to

gravity?

14. A plane flies at a speed of 250 km/hr relative to still air. There is a wind blowing at 80km/hr in the northeast

direction (that is, at 45o to the east of north). (a) In what direction should the plane head so as to fly due north? (b)

What is the speed of the plane relative to the ground?

15. An Earth satellite moves in a circular orbit 640 km above the Earths surface. The period of motion is 98.0 min.

(a) What is the speed of the satellite? (b) What is the free-fall acceleration at the orbit height?

16. A boy whirls a stone in a horizontal circle 2.0 m above the ground by means of a string 1.5 m long. The string

breaks, and the stone flies off horizontally striking the ground 10 m away. What was the centripetal acceleration of

the stone while in circular motion?