A baseball team is practicing throwing balls vertically upward to test their throwing arms. A player manages to throw a ball that reaches a maximum altitude of 10 m above the launch point, before falling back down. The acceleration due to gravity is 9.80 m/s 2 .
- (a) With what initial speed was the ball thrown?
- (b) How long did it take for the ball to reach its maximum altitude?
An automobile leaves St. John's University, first going due south at 88 km/h for 2 hours, and then turns on a road heading 20 degrees east of north at 55 km/h for 1.5 hours.
- (a) Calculate the (x, y) components of the net displacement of the automobile from the starting position, where the x-axis is east and y-axis is north.
- (b) Calculate the magnitude and direction of the automobile's net displacement. Given the magnitude in km and its direction using points of the compass, like for example, "25 degrees east of north".
An elevator together with its passenger's weights 5000 N. At a certain instant, the tension in its supporting cable is 6000 N. Determine the magnitude and direction of its instantaneous acceleration.
A 1300-kg car initially has a velocity of 22.2 m/s due south. It brakes to a stop over a 180-m distance.
- (a) What is the magnitude of the car's acceleration, in m/s 2
- (b) What average net force magnitude was necessary to stop the car?
- (c) Assuming the tires do not skid, what coefficient of static friction between tires and pavement is needed?
A car is initially moving at 35 km/h along a straight highway. To pass another car, it speeds up to 135 km/h in 10.5 seconds at a constant acceleration.
- (a) How large was the acceleration in m/s 2
- (b) How large was the acceleration, in units of g = 9.80 m/s 2?