ℙ𝕙𝕪𝕤𝕚𝕔𝕤 ℂ𝕙𝕒𝕡𝕥𝕖𝕣 𝟚 𝕊𝕖𝕔𝕥𝕚𝕠𝕟 𝔸𝕤𝕤𝕖𝕤𝕤𝕞𝕖𝕟𝕥

Calculate the acceleration of a car (in km/h * s) that can go from rest to 100 km/hrs in 10 s.

(100km/h - 0km/h)/(10s) = 10km/h/s

A ball is thrown straight up. What will be the instantaneous velocity at the top of its path? What will be its acceleration at the top? Why are your answers different?

0m/s; 9.8m/s^2; The velocity reaches zero due to its constant acceleration.

By how much does the speed of a vehicle moving in a straight line change each second when it is accelerating at 2 km/hours times second? At 4 km/hour times second? At 10 km/hrs. times second?

2km/h; 4km; 10km/h

For a freely falling object dropped from rest, what is the instantaneous speed at the end of the fifth second of fall? The sixth second?

50m/s; 60m/s (when g =10 m/ss)

A dragster going at 15 m/s North increases its velocity to25 m/s North in four seconds. What is its acceleration during this time interval?

A = Vf - Vi/t Vi = 5m/s Vf = 23m/s t = 4 seconds A = 23m/s - 5m/s /4s A = 4.5m/s^2

Calculate the instantaneous speed (in m/s) at the 10s mark for a car that accelerates at 2m/s^2 from a position of rest.

A = v - - - |X - - - - t - - - |10 = 2m/s 2 * 10 = 20 m/s

What is the meaning of free fall?

A free fall is an object dropping vertically, at the rate of 10m/s^2 due to gravity only.

a.) Find the speed required to throw a ball straight up and have it returned six seconds later. Neglect air resistance. b.) How high does the ball go?

Acceleration = 10m/s^2 Time = 6s (3s) Speed = ? a. v = at v = (10m/s^2)(3s) v = 30m/s ANSWER: 30m/s

Acceleration is the rate at which what happens?

Acceleration is a vector quantity that is defined as the rate at which an object changes its velocity. An object is accelerating if it is changing its velocity.

What quantity describes how quickly you change how fast you're traveling, or how quickly you change your direction?

Acceleration is the concepts that tells you how quickly your velocity changes, in other words, acceleration tells you how quickly your speed or direction changes, acceleration is the rate your velocity (not speed) changes. The acceleration of a car that travels in a straight line at a constant speed of 100 km/hour is zero.

What does the slope of the curve on a velocity versus time graph represent?

Acceleration. Explanation: velocity is the rate of change of position. The slope of a distance or position - Time graph is velocity. Acceleration is the rate of change, velocity. The slope of a velocity - Time graph is acceleration.

Which has more acceleration when moving in a straight line, a car increasing its speed from 50 to 60 km/h, or a bicycle that goes from 0 to 10 km/h in the same time? Defend your answer.

Both have equal changes in speed over equal time intervals which means their accelerations are also equal.

Does air resistance increase or decrease the acceleration of a falling object?

Deceases. With air resistance, acceleration throughout a fall gets less than gravity because air resistance affects the movement of falling object by slowing down. How much it slows the object down depends on the surface area of the object and its speed.

Why is it that an object can accelerate while traveling at a constant speed, but not at constant velocity?

Direction can change while traveling at a constant speed, But direction is constant velocity is constant.

We drive for one hour at 20 km/h. Then we drive for one hour at 30 km/h. What is our average speed?

First speed = 20km/h Time = 3hours Distance = 3 * 20 = 60km Second speed = 30 km/h Time = 4 hours Distance = 4 * 30 = 120km Total distance = 60 + 120 = 180km Total time = 3 + 4 = 7 hours Average speed = 180/7 = 25.71km/h

How far will an object move in one second if its average speed is 5m/s^2?

If an objects average speed is 5m/s, it will move 5m in 1s. It takes a freely falling object one second when falling from rest, since its acceleration is 10m/s^2.

What is the difference between instantaneous Speed and average speed?

Instantaneous speed is a scaler quantity, as it has no direction specified. On the other hand, average speed is the total distance traveled divided by the elapsed time.

What does the slope of the curve on a distance versus time graph represent?

It represents speed.

How far will a freely falling object have fallen from a position of rest when it's instantaneous speed is 10m/s?

It's average speed would be 5m/s.

What do we mean when we say that motion is relative? What is every day motion usually relative to?

Motion is always measured in reference to another object. Every day motion is relative to Earths' surface.

If the speedometer of a car reads a constant speed of 40km/hr, can you say that the car has a constant velocity? Why or why not?

No, the speedometer always reads 40 km/hr, You can say that the car had a constant speed, but not constant velocity. Average acceleration = (change in velocity)/(time it takes). Since the cars change in velocity is zero, its acceleration is zero.

Table 2.2 shows that the Insta and she is speed of an object dropped from rest is 10m/s after one second of all. Table 2.3 shows that the object has fallen only 5 m during this time. Your friend says this is incorrect, because distance traveled equals speed times time, so the object should fall 10 m. What do you say?

No, your friend is incorrect. The initial speed of the object was zero, final speed 10m/s. The average speed is (10/2) = 5m/s, so the object only drops 5 m in the first second.

What is the acceleration of a car moving along a straight line path that increases its speed from 0 to 100 km/hour in 10 seconds?

Since (average) acceleration = (change in velocity)/(Time it takes), the cars acceleration = (100km/h)/ (10s) = 10km/h/s)

What is the difference between speed and velocity?

Speed is the time rate at which an object is moving along a path, while velocity, on the other hand, is the rate and direction of an object's movement.

What is the acceleration of a car that travels in a straight line at a constant speed of 100 km/hour?

The acceleration of a car that travels in a straight line at a constant speed of 100 km/hour is zero. Average acceleration equals change in velocity divided by time it takes. Since the cars change in velocity is zero, it's acceleration is zero.

For a freely falling object dropped from rest, what is the acceleration at the end of the fifth second of fall? The sixth second? At the end of any elapsed time t?

The acceleration of a freely falling object is constant so it's acceleration at the end of the fifth second is the same as it's acceleration at the end of the term second. Or the end of the first or beginning of the 17th second. It's acceleration is 9.8 m/s/s which we will approximate as nearly 10 m/s/s.

If a freely falling rock where equipped and an odometer, would the readings for distance fallen each second stay the same, increase with time, or decrease with time?

The distance would increase quadratically for every second it fell.

Toss a ball upward. What is the change in speed each second on the way up? On the way down?

The freefall acceleration of any object, at any time, is 10 m/s^2. When you toss a ball into the air, its speed decreases by 10m/s each second as it goes up. On the way down, it's speed increases by about 10 m/s.

Speed is the rate at which what happens?

The rate at which distance changes with time.

Why does the unit of time enter twice in the unit of acceleration?

The reason is because, once for speed change, and again for time change.

a.) When a ball is thrown straight up, by how much does the speed decrease each second? Neglect air resistance. b.) After the ball reaches the top and begins its return back down, by how much does it speed increase each second? c.) Compare the times going up and coming down.

a.) 0m/s b.) 10m/s^2 c.) The Instantaneous velocity is zero, but the speed is changing at a rate of 10m/s^2

Does the speedometer of a car read instantaneous speed or average speed?

instantaneous speed

Calculate the average speed (in m/s) of a cheetah that runs 140 m in five seconds.

v = d/t v = 140m/5s = 28m/s^2

What is the appropriate equation for how fast an object fully falls from a position of rest? For how far that object falls?

v = gt; d = 1/2 gtt

A car going at 30 m/s undergoes an acceleration of 2 m/s squared for four seconds. What is its final speed? How far did it travel while it was accelerating?

v = u + at v = final speed u = initial speed a = acceleration t = time v = 30 + 2 * 4 = 38m/s = (30 +28) * 4/2 = 68 * 2 = 136m/s (30 - 2 = 28m; 28 * 4= 112m/s)

If you throw a ball straight upward at a speed of 10 m/s, how long will it take to reach zero speed? How long will it take to return to its starting point? How fast will it be going when it returns to its starting point?

vf = vi + at 0 = 10 - (10)x x = 1 second The speed will be the same, so 10 m/s at the same original position.

Calculate the speed (in m/s) of a skateboarder who accelerates from rest for three seconds down a ramp at an acceleration of 5 m/s^2.

vf = vi + at x = 0 + 3(5) = 15m/s

Calculate the hang time of an athlete who jumps a vertical distance of 0.75 meter.

Vf^2 = Vi^2 + 2ad 0 = x^2 + (2)(-10)x x = 0.4 seconds 2 * 0.4 = 0.8 seconds

Calculate the instantaneous speed of an apple that Falls freely from a rest position and accelerates at 10 m/s^2 for 1.5 seconds

Vi = 0m/s a = 10m/s^2 t = 1.5s Vf (final) = Vi (initial) + at Vf = 0m/s + 10m/s^2 (1.5) = 0m/s + 15m/s = 15m/s

You walk across the room at 2 km/h. Express this speed using abbreviated unit.

You're walk speed is 2 km/hr

a. If a freely falling rock World equipped with a speedometer, by how much would it speed readings increase with each second of fall? b.) Suppose the freely falling rock were drops near the surface of a planet where g = 20m/s^2. By how much would it's speed readings change each second?

a.) 9.8m/s b.) If a falling rock were somehow equipped with a speedometer, it would increase by g for every second of freefall. g is = 20m/s Therefore, it would increase by 20m/s for every second of freefall.

a. Calculate the average speed (in km/h) of Charlie, who runs to the store for kilometers away in 30 minutes. b. Calculate the distance (in km) that Charlie runs if he maintains this average speed for one hour.

a.) v = s/t = 4km/0.5 hours = 8km/hour b.) s = v (average) * t = 8km/hr * 1 hr = 8km

An object is dropped from rest and falls freely. After six seconds, calculate its instantaneous speed, average speed, and distance fallen?

1. To calculate instantaneous speed, the initial speed will be taken to be zero because the object was dropped from rest. The gravitational pull = 9.8m/s (approximately 10m/s) V = gt = 10 * 6 = 60 V = 60m/s 2. Average speed is defined as a change in distance divided by the change in time. To calculate the average speed you do: W (final speed + initial speed) Final speed = 60m/s Initial speed = 0m/s W = (60 + 0)/2 = 30 Average speed = 30m/s 3. To calculate distance fallen, the formula of speed will be used: Average speed = distance/time Distance = average speed * time = 30 * 6 = 180 The distance fallen = 180m

How far will a freely falling objects fall from rest in five seconds? Six Seconds?

125m; 180m

Light travels in a straight line at a constant speed of 300,000 km/s. What is the light's acceleration?

There is no acceleration because it's not turning and it's going at a constant speed. Acceleration = 0m/s^2

We drive a distance of 1 km at 20 km/h. Then we drive an additional distance of 1 km at 30 km/h. What is our average speed?

Total distance/time 20.32km/h

What to controls on a car cause a change in speed? What control causes only a change in velocity?

Two controls on a car that change in speed or the acceleration pedal and brake pedal. Three controls on a car can change its velocity, which are the accelerator pedal, brake pedal, and steering pedal. Since the cars change in velocity is zero, its acceleration is zero.

If humans originated in Africa and migrated to other parts of the world, sometime would be required for this to occur. At the modest rate of a mere 1 km per year, how many centuries would it take for humans Oregon eating in Africa to migrate to China, some 10,000 km away?

V = d/t 1 = 10,000/x x = 10,000 years 100 years = 1 century 10,000 = 100 centuries

Calculate the instantaneous speed and distance fallen for an object that falls freely from rest for eight seconds.

Vf = Vi + at X = 0 + 8(10) = 80m/s d = Vi + 1/2(a)(t)^2 d = 0 + 10/2(8)^2 = 320m