Help in Physics, please?
Thursday, December 31st, 2009
Does anyone know at least one?? And if you feel like it, explain how to get the answers?? Please & thank you. (:
1.) A swimmer is heading directly across a river 200m wide reaches the opposite bank in 6min 40s. She is swept downstream 300m. How fast can she swim in still water?
2.)The driver of a motorboat that that can move at 10m/s wishes to travel directly across strait in which the current flows at 5m/s. (a) At what angle upstream should the driver head the boat? (b) How long will it take to cross a distance of 1.6km?
3.) 3 forces, each havin magnitude of 30lbs, pull an object 120 degrees apart from each other. Which is true?
a. resultant force is 0.
b. resultant force is greater 30lb
c. resultant force 30lb
4.) Two vectors, R & S are R: north. & S: east. If the vector S is subtracted from vector R, then the vector T=R-S is which? SE, SW, NE, NW?
5.) Your motorboat can move at 30km/h in still water. How much time will it take you to move 12km upstream, in a river flowing at 6km/h?
6.)Bullet G is dropped, from rest, at the same time that another bullet H is fired horizontally from a rifle. If both bullets leave the same height above the ground, then…
a. G hits before H
b. both at the same time
c. H hits before G
d. not enough info
7.) Suppose that several projectiles are fired upward. Which one will be in the air longest?
a. farthest range, R
b. highest max elevation, h
c. one which has product of Rth is max
d. greatest initial velocity
8.) A golf ball is hit w/initial velocity of 60m/s at an angle of 130 degrees above the horizontal. How far does it travel?
9.) A plane flying horizontally at a speed of 50m/s and at an elevation of 160m drops a package of supplies. Two seconds later it drops a second package. How far apart will the two packages land on the ground?
10.) At what angle should a water-gun be aimed in order for the water to land with the greatest horizontal range? O or 30 or 45 or 90?
11.) A girl throws a stone straight down from a bridge. The stone leaves her hand w/velocity of 8m/s at height of 12m above the water. How much time does it take for the stone to hit the water?
12.) A mortar shell is launched with a velocity of 100m/s at an angle of 30 degrees above horizontal from a point on a cliff 50m above a level plain below. How far from the base of the cliff does the mortar shell strike the ground?
13.) An Olympic athlete throw a javelin at 4 different angles above the horizontal, each with the same speed: 30, 40, 60, & 80 degrees. Which 2 throws cause the javelin to land the same distance?
Credit Card Vending Machine
