LINEAR MOTION PROBLEMS 201 22. The average person passes out at an acceleration of 7 g (that is, seven times the gravitational acceleration on Earth). Suppose a car is designed to accelerate at this rate. How much time would be required for the car to acceler- ate from rest to 60.0 miles per hour? (The car would need rocket boosters!) 23. A certain car is capable of accelerating at a rate of 10.60 m/s". How long does it take for this car to go from a speed of 55 mi/h to a speed of 60 mi/h? 26. A car is traveling due east at 25.0 m/s at some instant. (a) If its constant acceleration is 0.750 m/s due east, find its velocity after 8.50 s have elapsed. (b) If its constant acceleration is 0.750 m/s2 due west, find its velocity after 8.50 s have elapsed. 27. A car traveling east at 40.0 m/s passes a trooper hiding at the roadside. The driver uniformly reduces his speed to 25.0 m/s in 3.50 s. (a) What is the magnitude and direc- tion of the car's acceleration as it slows down? (b) How far does the car travel in the 3.5-s time period? 29. A truck covers 40.0 m in 8.50 s while smoothly slowing down to a final velocity of 2.80 m/s. (a) Find the truck's original speed. (b) Find its acceleration. 33. ecp In a test run, a certain car accelerates uniformly from zero to 24.0 m/s in 2.95 s. (a) What is the magni- tude of the car's acceleration? (b) How long does it take the car to change its speed from 10.0 m/s to 20.0 m/s? (c) Will doubling the time always double the change in speed? Why? 34. ecp A jet plane lands with a speed of 100 m/s and can accelerate at a maximum rate of -5.00 m/s as it comes to rest. (a) From the instant the plane touches the runway, what is the minimum time needed before it can come to rest? (b) Can this plane land on a small tropical island airport where the runway is 0.800 km long? 38. A car accelerates uniformly from rest to a speed of 40.0 mi/h in 12.0 s. Find (a) the distance the car travels during this time and (b) the constant acceleration of the car.