Physics-Chapter 2.3 - 5.1 & 5.3 - Oct5th

By how much does the speed of an object in free fall change each second?

9.8 m/se

Can an object have a negative speed? Can it have a negative velocity?

An object cannot have negative speed, but it can have negative velocity. The negative sign indicates direction

The ___________________ on Earth is equal to 9.8 m/sec2

The acceleration due to gravity_

An astronaut carries a rock from the moon to Earth. Is the rock's mass the same on Earth as on the moon? Is its weight the same? Explain.

The rocks mass is the same. since mass is a measure of the amount of matter an object contains. The rocks weight is different since the acceleration due to gravity on the moon is different from earth

You drop a ball from the edge of a cliff. It lands 4 seconds later. a.Make a table showing the ball's speed each second for 4 seconds. b. What is the ball's average speed during the first second it is in free fall? c. What is the ball's average speed for the whole 4 second? d. What distance does the ball fall during the 4 seconds?

a. b. 9.8m/s c. 9.8m/s d. 39.2m

9. During a science experiment, your teacher drops a tennis ball out of a window. The ball hits the ground 3 seconds later. a. What was the ball's speed when it hit the ground? Ignore air resistance. b. What was the ball's average speed during the 3 seconds? c. How high is the window?

a. 29.4 m/sec b. 14.7 m/sec c. 44.1 m

10. Answer the following questions about mass and weight: a. How many newtons does a 5-kg backpack weigh on Earth? b. How many newtons does a 5-kg backpack weigh on the moon? c. Aya's mass is 45 kg. What is her weight in newtons on Earth? d. What is Aya's mass on the moon? e. What is Aya's weight in Newtons on the moon?

a. 49N (5 x 9.8) b. 8N (5x1.6) c. 441 N d. 45 Kg e. 72N

A ball is thrown straight up into the air. As it moves upward, its speed ______ by ____ each second. As it falls back down, its speed _____ by ____ each second.

decreases 9.8m/sec , increases 9.8m/sec

A falling object under the influence of only gravity is in _________________

free fall

Which two forces are equal when an object is at its terminal speed?

gravity and air resistance

What is the direction of air resistance on a falling object?

straight up

When the force due to gravity equals the force due to air resistance, the speed of a falling object is called its________________________________

terminal speed

Speed with direction is called ___________.

velocity

What is the difference between speed and velocity?

velocity is speed with direction

The force of gravity on an object is its ___________.

weight