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## FearOfPhysics.com: Position, velocity, and acceleration

[1] You sneeze while you are driving, and your eyes close for about 0.5 seconds during the sneeze. If you are driving at km/hr , how far does the car move during that time?

[2] An object has a constant acceleration of m/s2 . At a certain instant its velocity is m/s . What was its velocity seconds earlier?

[3]A car increases its speed from km/hr to km/hr in minutes . What is the acceleration of the car?

[4]In order to take off, an airplane must reach a speed of km/hr on the runway. What is the least constant acceleration it can have in order to take off from a runway km long?

[5] In good driving conditions (dry road, etc.), the brakes on a car with new tires can decelerate the car (slow it down) at m/s2 . If the car is traveling at m/s , how long does it take the car to stop? How far does it travel during this time?

[6] A car starts from rest and coasts down a hill with a constant acceleration. If it goes meters in seconds , find the acceleration and the velocity after this time.

[7] A car's velocity changes from m/s to m/s while covering meters . What is the acceleration of the car and the time it takes to do this?

[8]A ball is dropped from a bridge and strikes the water in seconds . How fast is it moving when it strikes the water, and what is the height of the bridge (neglect air resistance)?

[9]With what speed must a ball be thrown vertically upward to rise to a maximum height of meters ? And, how long will it be in the air?

[10]You are speeding on the freeway going miles per hour . You see a police car with its radar gun pointed right at you, and you try to slow down quickly. Your car's brakes give you an deceleration of 17 ft/s2 (a realistic number). How long will it take you to slow down to 55 miles per hour? Is it worth even trying to slow down?

[11]At the instant a traffic light turns green, a car starts from rest and accelerates at m/s2 . At this same instant, a truck overtakes the car traveling at the constant speed of m/s . How far from the traffic light will the car overtake the truck?

[12]You drop a rock from rest from a bridge and note that it hits the ground below seconds later. How high is the bridge?

[13]You throw a rock straight down at m/s from a bridge and note that it hits the ground below seconds later. How high is the bridge?

[14]Two trains are mistakenly heading toward each other. Train #1 is going at km/hr and train #2 is going km/hr . They see each other and begin braking when they are km apart. Train brakes provide a stopping acceleration of m/s2 . Is there are collision?

[15]You are standing on top of a building meters high, and throw a ball straight upward with a velocity of m/s . On the way down, the ball misses the building's top and falls to the ground. How long does it take to reach the ground, and how fast is the rock moving when it hits the ground?

[16]A truck starts from rest and moves with a constant acceleration of m/s2 . Find its speed and distance traveled after seconds have elapsed.

[17]A box slides down an incline with uniform acceleration. It starts from rest and attains a speed of m/s in seconds . What is the acceleration of the block, and the distance it moves in the first seconds ?

[18]A train running at m/s is slowed uniformly to a stop in s . Find the acceleration and the stopping distance of the train.

[19]A ball is thrown upward and returns to its starting point in seconds . Find its initial speed.

[20]\symbollook{middle,25} A truck is moving at m/s . The driver suddenly sees a vacant car blocking its path meters straight ahead. After a "reaction time" \bigdelta t, the driver applies the brakes, which gives the truck a deceleration of m/s2 . What is the minimum \bigdelta t, or "reaction time" the driver can have, to stop in time, and not hit the car?