Chapter 9 Review. Block: Date:

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1 Science 10 Chapter 9 Review Name: KEY Block: Date: 1. A change in velocity occur when the peed o an object change, or it direction o motion change, or both. Thee change in velocity can either be poitive or negative.. To calculate a change in velocity, ubtract the initial velocity rom the inal velocity. 3. Calculate the change in velocitie o the ollowing object: a) A boy i kiing orward down the mountain at 8m. He reache a teeper part o the mountain and increae hi velocity to 15m. v v v ( 15m ) ( 8m ) 7m i b) A car i moving orward at 50kmh. A young child run acro the treet and the car low to 30kmh. v v v ( 30km h) ( 50km h) 0km h i c) A young girl hit a tenni ball orward at a wall at 0m. The ball rebound o the wall at 15m back toward the girl. v v v ( 15m ) ( 0m ) 35m i d) A train i travelling orward at 30m. Ater ome time pae, the train ha not changed velocity and i till moving orward at 30m. v v v ( 30m ) ( 30m ) 0m i 4. A poitive change in velocity reult when an object that i already moving in a orward direction increae it velocity in the ame (orward) direction. 5. A negative change in velocity reult when an object that i already moving in a orward direction decreae it velocity in the ame (orward) direction. 6. I your initial and inal velocitie are equal, then your change in velocity would be zero and you would be moving at a contant velocity. 7. I velocity i contant your motion i aid to be uniorm, and i your velocity i changing (either poitive or negative), your motion i aid to be non-uniorm. 8. Acceleration i the rate at which an object change it velocity. 9. Like velocity, acceleration i alo a vector quantity, meaning you mut peciy both magnitude and direction when recording an object acceleration. 10. When comparing the acceleration o two dierent object, the object that change it velocity in a horter time interval or ha a greater change in velocity during the time interval, i aid to have a greater acceleration. 11. There are two type o acceleration, poitive and negative. 1. I a car i moving orward and increae it velocity in the orward direction, the acceleration i aid to be poitive. I a car i moving orward and decreae it velocity in the orward direction the acceleration i aid to be negative. 13. Acceleration which caue the object to decreae it peed i ometime called deceleration. 14. Poitive and negative acceleration both depend upon the direction that the object i initially moving. Generally, we deine an object moving orward a poitive and an object moving backward a negative. 15. I the change o velocity o an object i poitive it aid to be accelerating orward or poitively, i the change o velocity o an object i negative it aid to be accelerating backward or negatively.

2 16. A train i travelling orward at 0m, top and back up at 5m. What i the train change in velocity and what i the direction o the train acceleration? v v v ( 5m ) ( 0m ) 5m i The direction o the train acceleration i backward 17. I the acceleration o an object i in the ame direction a the velocity, what happen to the velocity o the object? I an object accelerate in the ame direction that the object i already moving, then the object velocity will increae. 18. I the acceleration o an object i in the oppoite direction a the velocity, what happen to the velocity o the object? I an object accelerate in the oppoite direction to the velocity, then the object velocity will decreae. 19. Decribe the concept behind having airbag in automobile (be ure your decription include the acceleration that occur in a car accident.) The driver o a car i moving at the ame velocity a the car when driving. When you get into a car accident, the car and the driver both decelerate to zero very quickly. The idea behind airbag i to prolong the topping time that occur when you get into a car accident. When you hit the air bag your change in velocity take a longer period o time a compared to imply triking the dahboard or the car. Thi reult in a maller acceleration. I your acceleration i maller, there i le chance o injury. 0. Poition-time graph can be ued to repreent the motion o an object travelling at contant velocity or changing rom contant velocity to another. Velocity-time graph can be ued intead to repreent motion o an object whoe velocity i changing. Velocity-time graph provide inormation about an object velocity and acceleration. 1. The lope o a line on a velocity-time graph repreent the change in the object velocity. Change in velocity i alo known a acceleration, thereore the lope o a velocity-time graph alo repreent an object acceleration.. Decribe how you would calculate an object acceleration uing the lope o a velocity-time graph. Slope can be calculated by calculating the change in velocity over a time interval and dividing it by that time interval. v rie Since the lope o a velocity-time graph equal the acceleration, a t run 3. The SI unit or acceleration i m. 4. Decribe what i occurring to an object that i accelerating orward at 5.0m. When an object i accelerating at 5.0m it i increaing it velocity 5.0m every 1.0 that pae by. Ater econd the object ha increaed it velocity twice by 5m, giving the object a velocity o 10m i it tarted at ret. 5. I an object velocity i changing at a contant rate, it ha a contant acceleration. 6. Average acceleration i repreented by the lope o a velocity-time graph.

3 Ue the velocity-time graph below to anwer quetion For each o the time interval below, decribe the velocity and acceleration o the object. a) 0 The object tart at ret and increae it velocity at a contant rate until it reache 8m [E]. The object acceleration i orward (eat) and poitive (+4m ). b) 6 The object velocity tay contant at 8m [E] or thi time interval. The object acceleration i zero. c) 6 10 The object tart at 8m [E] and decreae it velocity at a contant rate until it reache 0m. The object acceleration i backward (wet) and negative (-m ). 8. Calculate the acceleration o the ollowing object: a) A woman riding a bicycle i travelling orward at 5m and increae her velocity to 0m in 5. v v vi ( 0m ) ( 5m ) 15m v 15m a 3m t 5 b) You throw a tenni ball at a wall and it hit the wall going 5m. The ball rebound o the wall at 15m back toward you in 0.5. v v vi ( 15m ) ( 5m ) 40m v 40m a 80m t 0.5 c) You are driving a car at 0m. Suddenly a dog run out in ront o your car and you low to a top in. v v vi ( 0m ) ( 0m ) 0m v 0m a 10m t 9. You can alo ue an acceleration to calculate either a change in velocity or time. I you know acceleration and change in time, you multiply acceleration by time to calculate the change in velocity. I you know acceleration and change in velocity, you divide change in velocity by acceleration to calculate the change in time.

4 30. Calculate the change in velocity o the ollowing object: a) A runner at ret accelerate orward at.0m or 6. v ( a) ( t) ( m ) (6) 1m b) A car creeche to a halt with a negative acceleration o -15m in 1.5. v ( a) ( t) ( 15m ) (1.5 ).5m c) A baeball that i hit by a bat. The ball experience an acceleration o 00m or 0.5. v ( a) ( t) ( 00m ) (0.5) 50m 31. Calculate the time interval o the ollowing cenario: a) A car moving 0m orward low to a top. I the car decelerate at 5m, how long doe it take or the car to come to a top? v v vi ( 0m ) ( 0m ) 0m v 0m t 4 a 5m b) A train going 0m increae it velocity to 40m in the ame direction. I the train accelerate at 4m, how long doe the train accelerate or? v v vi ( 40m ) ( 0m ) 0m v 0m t 5 a 4m c) A girl on rollerblade i travelling 9m in the orward direction; he low down to m in the ame direction, how long doe he decelerate or i he decelerate at 1m? v v vi ( m ) ( 9m ) 7m v 7m t 7 a 1m 3. Gravity i an attractive orce that act between two or more object. The mot common example o which i between any object near the Earth and the Earth itel. 33. Gravity i a contant negative acceleration that object experience when they all reely near the Earth urace. 34. Decribe the velocity and acceleration that a ball experience rom the time it i toed in the air until it hit the loor. When a ball i thrown in the air it ha an initial poitive velocity (poitive being up in direction.) Gravity tart acting on the ball the moment it leave your hand. The acceleration i negative and contant and act on the ball the entire proce. The ball low in velocity and when it reache it maximum height, it ha a velocity o zero, ater which the ball tart increaing it velocity negatively (negative being down in direction) until it hit the loor. 35. Object that are dropped that have dierent mae accelerate at the ame rate. 36. Today we undertand that two object dropped rom the ame height hould hit the ground at the ame time regardle o the their mae. Decribe why a lat piece o paper might take longer to hit the loor i it wa dropped at the ame height and at the ame time a a tenni ball. The reaon that a lat piece o paper may take longer to hit the loor than the tenni ball may be attributed to air reitance. Air reitance i a riction-like orce that oppoed motion o object that move through the air. Since the piece o paper ha more urace area or air reitance to act on, it may take longer to hit the ground than the tenni ball.

5 37. Galileo irt propoed that in the abence o air reitance, all object regardle o their weight, all at the ame contant acceleration. Thi type o acceleration i called acceleration due to gravity. The value o which i 9.8m downward. 38. Calculate the change in velocity o the ollowing object: a) A man jump o a diving board and hit the pool water below later. v ( g) ( t) ( 9.8m ) () 19.6m b) A rock i dropped o a cli and hit the ground 5 later. v ( g) ( t) ( 9.8m ) (5) 49m 39. Calculate the time interval or the ollowing cenario: a) A man jump o a diving board and hit the pool water below with a velocity o 5m. v v vi ( 5m ) (0m ) 5m v 5m t. 6 a 9.8m b) A girl i on a trampoline. She jump up with a velocity o 1m and land on her way down with a velocity o -1m. v v vi ( 1m ) ( 1m ) 4m v 4m t. 4 a 9.8m Vocabulary to Know: Write a concie deinition o each o thee term ound in thi chapter. Acceleration due to gravity: Acceleration: Air reitance: Average acceleration: Change in velocity: Contant velocity: Contant acceleration: Deceleration: Gravity: Negative change in velocity: Negative acceleration: Poitive acceleration: Poitive change in velocity: Velocity-time graph: Symbol to Know: Indicate what each o the ollowing ymbol repreent and whether they are a calar quantity or a vector quantity. a acceleration (vector) t v i v v time interval (calar) initial velocity (vector) inal velocity (vector) change in velocity (vector)