7. A car can accelerate at 4 m./sec.2. How long will it take to reach 90 km./h. from rest? (ans.: 6.25)

PROBLEM 2.27 A girl is riding her bicycle. When she gets to a corner, she stops to get a drink from her water bottle. At that time, a friend passes by her, traveling at a constant speed of 10.0 m/s. 32. After 25 s, the girl gets back on her bike and travels with a constant acceleration of 2.5 m/s². How long does it take for her to catch up with her friend? c. 20.70 s d. 21.70 s а. 19.70 s b. 18.70 s 33. If the girl had been on her bike and rolling along at a speed of 1.5 m/s when her friend passed, what constant acceleration would she need to catch up with her friend in the same amount of time? c. 0.709 m/s² d. 0.609 m/s² а. 0.809 m/s² b. 0.909 m/s2

4. An airplane initially at rest accelerates at 4.5 m/s² down a runway. It reaches a velocity of 33 m/s before it lifts off the ground. a. How much time does the airplane spend on the runway before taking off? gintarit no1 Inemsonigy insod mot avhh limm om bas boos qia o rot ylipalay agstovsods bas busbe ogsnove ori bait b. Find the distance the airplane travels before it lifts off.

A motorist traveling at a constant 15 m/s (54 km/h, or about 34 mi/h) passes a school crossing where the speed limit is 10 m/s (36 km/h, or about 22 mi/h). Just as the motorist passes the school-crossing sign, a police officer on a motorcycle stopped there starts in pursuit with constant acceleration 3.0 m/s2 . (a) How much time elapses before the officer passes the motorist? At that time, (b) what is the officer’s speed and (c) how far has each vehicle traveled?