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**Group Practice!**

**Grab a whiteboard and a box set **

• A motorboat is traveling due north in calm water at a speed of 6.0 m/s. The operator puts the motor in reverse and the boat receives an acceleration of -1.5 m/s 2 . • How long after the boat is put into reverse does it momentarily come to a stop?

• How far has the boat traveled while it decelerated to a stop?

• A car moving at 32.0 m/s hits a wall and stops in 0.020 s. Calculate the acceleration stopping the car.

• The driver of a pick-up truck going 100. km/h applies the brakes, giving the truck a uniform deceleration of 6.50 m/s 2 while it travels 20.0 m. • What is the velocity of the truck in m/s at the end of this distance?

• How much time does it take the driver to **come to a stop**?

• A rocket accelerates from rest at a rate of 40.0 m·s -2 until it reaches a velocity of 1800. m·s -1 . How much time does this take?

• A jet aircraft being launched from an aircraft carrier is accelerated from rest along a 94m track for 2.5 s. What is the launch speed of the plane?

• A car accelerates at 2.5 m·s -2 E for 16 s. After this time the car is moving at 10.0 m/s W. Calculate its initial velocity.

• An Olympic biathlete shoots a bullet at a target 50.0 m away. If the average velocity of the bullet is 323 m·s -1 How much time does it take for the bullet to reach the target?

• From the moment a 40.0 m/s fastball touches the catcher’s mitt until it is completely stopped takes 0.0125 s. Calculate the average acceleration of the ball as it is being caught.

• Top-fuel drag racers are able to uniformly accelerate at 12.5 m/s 2 from rest to 100. m/s before crossing the finish line. How much time elapses during that acceleration?

• How far has the drag racer traveled down the track in that time?

• An Alaska Airlines jet traveling at 88.0 m/s lands on a runway and comes to a stop 11.0 seconds later before taxiing to the gate.

• What is the acceleration of the jet as it lands?

• How long does the runway need to be for this jet to land?

• A motorcycle traveling at 16 m/s accelerates at a constant rate of 4.0 m/s 2 over a distance of 50. m. What is its final velocity?

• Police find skid marks 60. m long on a highway showing where a car made an emergency stop. Assuming that the acceleration was -10. m/s 2 (about the maximum for dry pavement), how fast was the car going when it began to skid? • Was the car exceeding the 80 km/h speed limit? (show your work to justify your answer).