Quiz 3

14.7 m/s

A man leans over the edge of a cliff and throws a rock upward at 4.9 m/s. Neglecting air resistance, two second later the rock's speed is Zero 4.9 m/s 14.7 m/s 9.8 m/s

About 30 m/s

A pot falls from a ledge and hits the ground 45 m below. The speed with which it hits the ground is About 60m/s More than 120m/s About 120m/s About 30 m/s

60m/s

At one instant an object in free fall is moving downward at 50meters per second. One second later its speed should be about 60m/s 50m/s 100m/s 25m/s

2 sec

If a projectile is forced straight up at a speed of 10m/s the total time to return to its starting position is about 10 seconds 1 second 20 seconds 2 seconds

9.8 meters per second per second

If you drop an object, it will accelerate downward at a rate of 9.8 meters per second per second. If you instead throw it downwards, its acceleration (in the absence of air resistance) will be 9.8 meters per second per second Greater than 9.8 meters per second per second Less than 9.8 meters per second per second Zero

Increasing

In each second of fall, the distance a freely falling object will fall is

About 180 m

It takes 6 seconds for a stone to fall to the bottom of a mine shaft. How deep is the shaft? About 180 m More than 200 m About 60 m About 120 m

Neither, they will both hit with the same speed

Someone standing at the edge of a cliff throws one ball straight up and another ball straight down at the same initial speed. Neglecting air resistance, the ball to hit the ground below the cliff with the greater speed will be The one thrown downward The one thrown upward Neither, they will both hit with the same speed Impossible to tell

4

Ten seconds after starting from rest, a car is moving at 40m/s. What is the car's acceleration in meters per second per second? 10 4 2.8 40