Physics Chapter 3

constant velocity always implies constant speed

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

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

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

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

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?

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?

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

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.

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

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*

acceleration.

Disregarding air resistance, objects fall with constant

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.

the same amount.

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

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.

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.

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?

roughly 30 m/s (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?

increasing

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

-neither -- they will both hit with the same speed. (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. The ball to hit the ground below the cliff with the greater speed will be

more than 100 m/s. *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*

Twelve seconds after starting from rest, an object falling freely will have a speed of

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 0, acceleration due to gravity is always directed downward (with a magnitude of 9.8 m/s2))

When a ball thrown upward reaches its highest point, its acceleration is?

is zero.

When a ball thrown upward reaches its highest point, its velocity is?

velocity is zero and its acceleration is about 10 meters per second per second.

When a rock thrown straight upwards gets to the exact top of its path, its

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?

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*

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

10 m/s

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?

Constant speed

Steady speed.

Average speed =

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

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

Acceleration =

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

Motion

is relative.

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.

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

about 50 m/s (5 sec X 10m/s²) 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 back

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?

Changing velocity

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

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

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.