Physics Chapter 3

No, unless you could look outside the vehicle, you would not be aware that it was moving

If a car moved with absolutely constant velocity (no bumps at all), would you be aware of motion?

constant velocity always implies constant speed

If a car moves with a constant velocity, does it also move with a constant speed?

10 m/s (because earth's gravitational force exerts an acceleration of about 10 m/s on an object)

If a freely falling object were somehow equipped with a speedometer, its speed reading would increase each second by about *Give an explanation*

3000 m/s Calculated using acceleration formula: P=∆v/t with (v) as the variable

If a rocket initially at rest accelerates at a rate of 50 m/s2 for one minute, its speed will be

greater than the second before ( this is because during free fall, an object accelerates based on a constant acceleration. Acceleration is a change in velocity. So each second the object accelerates, it adds to the velocity that the object is moving. This increases the distance the object travels each second second it falls from the previous second it fell )

If an object falling freely were somehow equipped with an odometer to measure the distance it travels, then the amount of distance it travels each succeeding second would be greater than the second before. less and less each second. constant. doubled. *Give an explanation*

Average speed =

total distance covered ---------------------------- time interval

Distance fallen in free fall, from rest;

*d = ½ gt²*

Velocity acquired in free fall, from rest;

*v = gt*

less than the speed it had when thrown upwards. Although the instantaneous speed at a point of equal elevation in a path are the same weather an object is moving upward or downward. This olny work if there was no air resistance. As the object falls after being thrown up, air molecules collide with object slowing it down

A ball is thrown upwards and caught when it comes back down. In the presence of air resistance, the speed with which it is caught is always A ball is thrown upwards and caught when it comes back down. In the presence of air resistance, the speed with which it is caught is always -the same as the speed it had when thrown upwards. -less than the speed it had when thrown upwards. -more than the speed it had when thrown upwards. -impossible to determine. *Give an explanation*

The same Because the instantaneous speed at a point of equal elevation in a path are the same weather an object is moving upward or downward.

A ball is thrown upwards and returns to the same position. Compared with its original speed after release, its speed when it returns is about twice as much. half as much. four times as much. the same. *Give an explanation*

20 m/s. (since earth gravitational force exerts an acceleration of about 10 m/s on an object, and this planet is twice as much than you just multiply earths by 2)

An object at rest near the surface of a distant planet starts to fall freely. If the acceleration there is twice that of the Earth, its speed one second later would be *Give an explanation*

about 50 m/s They are asking you, when you throw a ball in the air at what SPEED does it take to get a ball to get the ball at it highest point with a zero velocity So on earth it takes an object travels 10 m/s, so the first 5 seconds would be you throwing it up the second 5 seconds would be the object falling directly back 5 sec X 10m/s² = 50 m/s

A ball is thrown upwards. Neglecting air resistance, what initial upward speed does the ball need to remain in the air for a total time of 10 seconds? A ball is thrown upwards. Neglecting air resistance, what initial upward speed does the ball need to remain in the air for a total time of 10 seconds? about 100 m/s about 60 m/s about 80 m/s about 50 m/s about 110 m/s *Give an explanation*

directed downward ( The acceleration due to gravity is always directed downward (with a magnitude of 9.8 m/s²), regardless of the object's velocity.)

A ball tossed vertically upward rises, reaches its highest point, and then falls back to its starting point. During this time the acceleration of the ball is always *Give an explanation*

100 m Calculated using: d=(1/2)at²

A car accelerates at 2 meters/s/s. Assuming the car starts from rest, how far will it travel in 10 s?

zero (because if it's velocity is constant then it must have an acceleration of zero)

A car maintains a constant velocity of 100 km/hr for 10 seconds. During this interval its acceleration is *Give an explanation*

zero (Because if no other forces are acting on the puck, once one force acts on it, the puck enters into mechanical equilibrium, and according to newton's 1st law an object in motion tends to stay in motion, due to the object inertia properties)

A hockey puck is set in motion across a frozen pond. If ice friction and air resistance are neglected, the force required to keep the puck sliding at constant velocity is A hockey puck is set in motion across a frozen pond. If ice friction and air resistance are neglected, the force required to keep the puck sliding at constant velocity is zero. equal to its weight divided by its mass. equal to its weight. equal to the product of its mass times its weight. *Give an explanation*

10/.5=20

A horse gallops a distance of 10 kilometers in a time of 30 minutes. Its average speed is

is still -9.8 m/s2. The acceleration due to gravity is always -9.8 m/s/s, regardless of the ball's velocity.

A person drops a ball from rest, and the ball accelerates downward at a rate of -9.8 m/s2. If the person throws the ball upward, after the person lets go of the ball, its acceleration is? *Give an explanation*

The second ball's maximum height is more than twice as high. (It takes twice as long for the second ball to reach its maximum height, but remember that it also has a higher average velocity. In fact, it gets four times higher than the first ball.)

A person throws a ball upward with an initial speed of 15 m/s, and then a second (identical ball) with an initial speed of 30 m/s. How much higher up is the maximum height of the second ball, compared to that of the first ball? *Give an explanation*

0 ( because the object velocity never changes, which means it never accelerates)

An object covers a distance of 8 meters in the first second of travel, another 8 meters during the next second, and 8 meters again during the third second. Its acceleration in meters per second per second is approximately *Give an explanation*

100 m/s. They are asking for SPEED This is because each second the object will accelerate 20 m/s, so if you multiply 20*5=100 m/s²

An object falls freely from rest on a planet where the acceleration due to gravity is 20 meters per second squared. After 5 seconds, the object will have a speed of

250 m. they are asking for DISTANCE so you use d=(1/2)at²

An object falls freely from rest on a planet where the acceleration due to gravity is twice as much as it is on Earth. In the first 5 seconds it falls a distance of

is constant in time. (Since the inclination of the plane doesn't change with position, the component of gravity pulling the ball down along the incline doesn't change, so the acceleration is constant.)

As a ball rolls down an inclined plane (say with an angle of incline of 30°), the ball's acceleration *Give an explanation*

50 meters per second because in earth gravity an object thrown up in to the air decelerates 10 m/s

At one instant a heavy object in air is moving upward at 50 meters per second. One second later its speed is approximately *Give an explanation*

60 m/s. Because during free fall on earth an object accelerates 10 m/s

At one instant an object in free fall is moving downward at 50 meters per second. One second later its speed should be about *Give an explanation*

get farther apart. The drop descending earlier goes faster than the ones after it because it has been traveling a longer time under gravities acceleration of about 9.8 m/s² which is being added to it's velocity every second.

Consider drops of water that leak at a steady rate from a dripping faucet. As the drops fall they Consider drops of water that leak at a steady rate from a dripping faucet. As the drops fall they -get farther apart. -get closer together. -remain at a relatively fixed distance from one another. *Give an explanation*

6 km/h/s. Calculated using a=v/t

If a car increases its velocity from zero to 60 km/h in 10 seconds, its acceleration is 0.

10 m/s They are asking you, when you throw a ball in the air at what SPEED does it take to get a ball to get the ball at it highest point with a zero velocity So on earth it takes an object travels 10 m/s, so the first second would be you throwing it up the second second would be the object falling directly back since it only has one second to fall it:s velocy wont increase, and it will land in 2 seconds

Disregarding air drag, how fast must you toss a ball straight up in order for it to take 2 seconds to return to the level from which you tossed it? 10 m/s 15 m/s 7.5 m/s 5 m/s 20 m/s *Give an explanation*

acceleration. a falling objects speed is always changing, and since velocity is a speed and direction then that is changing too. It's moving downward from one direction to another so it's distance is changing each second. However it acceleration stays around 10-9.8 m/s. It just keeps changing it's velocity that amount each second.

Disregarding air resistance, objects fall with constant velocity. acceleration. distances each successive second. speed. *Give an explanation*

Speed =

Distance ------------ Time

Average speed is the speed averaged over a span of time Instantaneous speed would be the speed any any given instant within that span of time

Distinguish between instantaneous speed and average speed.

velocity is the speed and direction that an object is moving. Acceleration is the rate in which velocity changes over time.

Distinguish between velocity and acceleration.

the same amount. (Because the rock's velocity may have changed, but it's acceleration as long as its drop on earth stays around 10 m/s)

Drop a rock from a 5-m height and it accelerates at 10 m/s2 and strikes the ground 1 s later. Drop the same rock from a height of 2.5 m and its acceleration of fall is about Drop a rock from a 5-m height and it accelerates at 10 m/s2 and strikes the ground 1 s later. Drop the same rock from a height of 2.5 m and its acceleration of fall is about twice as much. four times as much. half as much. the same amount. *Give an explanation*

take the initial speed which is 0 and the final speed in the case of earth by the first second the acceleration would be 10 m/s. Then you divide that by two. Which gives you 5 m/s

How do you find the average speed before the First second, when an object is falling before it hits its consistent gravitational acceleration.

The acceleration for the 30° ramp is higher. Since the incline is steeper, the acceleration is higher.

How does the acceleration of a ball rolling down an inclined plane with an angle of incline of 30° compare to that of a ball rolling down an inclined plane with an angle of incline of 15°? *Give an explanation*

Speed

How fast something moves; the distance traveled per unit of time.

6 m/s Calculated using acceleration formula: P=∆v/t

If a car accelerates from rest at 2 meters per second per second, its speed 3 seconds later will be about

change by the same amount each second (acceleration means that there's bean a change in velocity, so acceleration means that velocity is constantly changing. Since the object is accelerating consistently, then velocity must change by the same amount since they are directly related) It can not be "change by varying amounts depending on its speed." because the acceleration is constant not varying

If an object moves with constant acceleration, its velocity must -always decrease. -change by the same amount each second. -change by varying amounts depending on its speed. -be constant also. *Give an explanation*

Changing velocity

If either the speed or the direction changes (or both change), then the velocity changes.

9.8 meters per second per second. because Throwing an object downward or dropping an object downward does not affect its rate of acceleration, which is 9.8 m/s² on earth

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 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 -greater than 9.8 meters per second per second. -less than 9.8 meters per second per second. -9.8 meters per second per second. *Give an explanation*

roughly 30 m/s (The velocity of a free-falling object is given by acceleration due to gravity times the time interval. So for this case v = 10 m/s2 × 3 s = 30 m/s.)

Ignoring wind resistance, how fast is a ball moving three seconds after being dropped from rest? *Give an explanation*

increasing ( Because an object in free fall accelerates due to gravity)

In each second of fall, the distance a freely falling object will fall is? increasing. about 5 m. about 10 m. the same, but not 5 m or 10 m. none of these *Give an explanation*

about 180 m Calculated using: d=(1/2)at²

It takes 6 seconds for a stone to fall to the bottom of a mine shaft. How deep is the shaft?

Linear motion

Motion along a straight-line path.

Constant velocity

Motion in a straight line at a constant speed.

Free Fall

Motion under the influence of gravity only.

Vector quantity

Quantity in physics that has both magnitude and direction.

-neither -- they will both hit with the same speed. because Throwing an object downward or dropping an object downward does not affect its rate of acceleration, which is 9.8 m/s² on earth

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 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. *Give an explanation*

Instantaneous speed

Speed at any instant.

Constant speed

Steady speed.

Acceleration

The rate at which velocity changes with time; the change in velocity may be in magnitude, or direction, or both.

Velocity

The speed of an object and a specification of its direction of motion.

more than 100 m/s. ( this is because during free fall, an object accelerates based on a constant acceleration. *In the case of earth which has an gravitational force on an object accelerating it 10 m/s. You just multiply 10ms X 12 sec= 120 m/s* Acceleration is a change in velocity. So each second the object accelerates it adds to the velocity that the object is moving. This increases the distance the object travels each second second it falls from the previous second it fell )

Twelve seconds after starting from rest, an object falling freely will have a speed of more than 100 m/s. 50 m/s. 10 m/s. 100 m/s. *Give an explanation*

acceleration: m/s² Speed: m/s

What's is the unit for acceleration and What's the unit for speed

It will be the relative speed 100-98= 2 km.h

What's the impact speed when a car moving at 100 km/h bumps a car moving in the same direction 98 km/h?

is directed downwards. (Although the velocity is zero, the acceleration is still directed downwards. The acceleration due to gravity is always directed downward (with a magnitude of 9.8 m/s2), regardless of the object's velocity.)

When a ball thrown upward reaches its highest point, its acceleration is? *Give an explanation*

is zero. (Since the ball has reached its highest point, it can't be moving upwards anymore.)

When a ball thrown upward reaches its highest point, its velocity is? *Give an explanation*

velocity is zero and its acceleration is about 10 meters per second per second. Once at the top of its path the rock hits a zero velocity before it changes direction, however on Earth an objects acceleration is always about 10-9.8 m/s²

When a rock thrown straight upwards gets to the exact top of its path, its When a rock thrown straight upwards gets to the exact top of its path, its -velocity is about 10 m/s and its acceleration is zero. -velocity is zero and its acceleration is about 10 meters per second per second. -velocity is about 10 m/s and its acceleration is about 10 meters per second per second. -velocity is zero and its acceleration is zero. -none of these *Give an explanation*

You are most aware of the motion of a vehicle when during acceleration.

When are you most aware of motion in a moving vehicle - when it is moving steadily in a straight line or when it is accelerating?

none of the above ( because, It has mass so it must have inertia, it's going in a circle and change direction so its velocity is changing, if it velocity is changing then that means it's acceleration is changing as well, because acceleration is the change in velocity)

While a car travels around a circular track at a constant speed, its inertia is zero. velocity is zero. acceleration is zero. none of the above *Give an explanation*

velocity increases (Acceleration stays consistent around 10-9.8, but velocity increases the farther it falls. )

While an object near the Earth's surface is in free fall, what is increasing? *Give an explanation*

Acceleration (along a straight line) =

change in speed --------------------- time interval

Acceleration =

change of velocity ----------------------- time interval

Motion

is relative.