RKNY
Feb5-07, 12:30 AM
Problem 1
1. The problem statement, all variables and given/known data
A golfer rides in a golf cart at a speed of 3.10 m/s for 29.0 s. She then gets out of the cart and starts walking at an average speed of 1.20 m/s. For how long (in seconds) must she walk if her average speed for the entire trip, riding and walking, is 2.10 m/s?
2. Relevant equations
time = distance x avg. speed
3. The attempt at a solution
Taking the distance traveled from the riding -
3.10 m/s x 29.0 s = 90 m
Tried numerous ways such as taking another 90m and using the 1.20 as a given
Problem 2
1. The problem statement, all variables and given/known data
A sprinter explodes out of the starting block with an acceleration of +3.5 m/s2, which she sustains for 1.2 s. Then, her acceleration drops to zero for the rest of the race.
(a) What is her velocity at t = 1.2 s.
(b) What is her velocity at the end of the race?
2. Relevant equations
Avg. Veloctiy = displacement/elapsed time
Avg. Accel. = Change in veloc./elapsed time
3. The attempt at a solution
(a) 3.5 m/s^2 x 1.2 s = 4.2 m/s
(b) I believe that you would have to use -3.5 because of the decrease in acceleration but I can't seem to know how to get anything or figure anything out after that.
1. The problem statement, all variables and given/known data
A golfer rides in a golf cart at a speed of 3.10 m/s for 29.0 s. She then gets out of the cart and starts walking at an average speed of 1.20 m/s. For how long (in seconds) must she walk if her average speed for the entire trip, riding and walking, is 2.10 m/s?
2. Relevant equations
time = distance x avg. speed
3. The attempt at a solution
Taking the distance traveled from the riding -
3.10 m/s x 29.0 s = 90 m
Tried numerous ways such as taking another 90m and using the 1.20 as a given
Problem 2
1. The problem statement, all variables and given/known data
A sprinter explodes out of the starting block with an acceleration of +3.5 m/s2, which she sustains for 1.2 s. Then, her acceleration drops to zero for the rest of the race.
(a) What is her velocity at t = 1.2 s.
(b) What is her velocity at the end of the race?
2. Relevant equations
Avg. Veloctiy = displacement/elapsed time
Avg. Accel. = Change in veloc./elapsed time
3. The attempt at a solution
(a) 3.5 m/s^2 x 1.2 s = 4.2 m/s
(b) I believe that you would have to use -3.5 because of the decrease in acceleration but I can't seem to know how to get anything or figure anything out after that.