Physics Final Exam (Ch. 1, 2, 3)

In which of the following cases is the displacement's magnitude half the distance traveled?

5 steps east followed by 10 steps west.

A European sports car dealer claims that his car will accelerate at a constant rate from rest to 100 km/hr in 8.00 s. If so, what is the acceleration? (Hint: First convert speed to m/s.)

Acceleration = change in velocity/change in time. So 27.78-0/8 = 3.47 m/s^2

A jogger runs halfway around a circular path with a radius of 60 m. What, respectively, are the magnitude of the displacement and the distance jogged?

Circle: so the distance travelled is 2pi(r) and the displacement is 2(r). Given that knowledge the distance travelled is 2pi(60) which is 188.49 while the displacement is 2(60)= 120m.

A bird, accelerating from rest at a constant rate, experiences a displacement of 28 m in 11 s. What is the final velocity after 11 s?

Equation used is (displacement) = V(initial)*(time) + 1/2a(t)^2 So 28 = 0 (at rest) + 1/2(a)(11)^2 28 = 1/2(a)(11)^2 56 = a(11)^2 56/121 = a 0.463 m/s^2 = a So acceleration is found therefore we can use Vf=Vi + at Vf = 0 + 0.463(11) Vf = 5.093 m/s

A rock is thrown straight up with an initial velocity of 19.6 m/s. What time interval elapses between the rock's being thrown and its return to the original launch point? (Acceleration due to gravity is 9.80 m/s2 .)

Equation used: (displacement) = Vi(t) + 1/2(a)(t)^2 So because its being thrown up and then coming back, it is at its original position therefore the displacement is 0. 0 = 19.6m/s(t) + 1/2(9.81m/s^2)t^2 We cancel the t's 0 = 19.6m/s + 1/2(9.81m/s^2)t -19.6m/s = 1/2(9.81) t -19.6m/s/4.905 = t 3.99s = t

Mt. Everest is more than 8 000 m high. How fast would an object be moving if it could free fall to sea level after being released from an 8000-m elevation? (Ignore air resistance.)

Equation used: Vf^2 = Vi^2 + 2a(displacement) So it is being dropped from rest. Vf^2 = 0^2 + 2(9.81)(8000m) Vf^2 = sqrt(156960) = 396.18 m/s

Note the expression: y= A/x^3. Which statement is most consistent with this expression?

If x is halved, y is multiplied by eight.

Which one of the choices below represents the preferred practice regarding significant figures when adding the following: 12.4 + 11 + 67.37 + 4.201

In addition it is always the least amount of sig fig. The answer is 95.

In one-dimensional motion where the direction is indicated by a plus or minus sign, the average velocity of an object has which of the following properties?

It can be positive, negative, or zero.

In one-dimensional motion, the average speed of an object that moves from one place to another and then back to its original place has which of the following properties?

It is positive.

Areas always have dimensions ____ while volumes always have dimensions ____.

L^2, L^3

The distance of the earth from the sun is 93,000,000 miles. If there are 3.15 x 10^7 seconds in one year, find the speed of the Earth in its orbit about the sun.

Radius is 93,000,000 Distance is 2pi(r) v = distance/time So it is = 2pi(93,000,000)/3.15x10^7 = 18.55 miles/sec

A baseball thrown from the outfield is released from shoulder height at an initial velocity of 29.4 m/s at an initial angle of 30.0° with respect to the horizontal. If it is in its trajectory for a total of 3.00 s before being caught by the third baseman at an equal shoulder-height level, what is the ball's net vertical displacement during its 3-s trajectory?

Since it is being thrown up and then coming down, the net displacement is zero.

Jack pulls a sled across a level field by exerting a force of 110 N at an angle of 30° with the ground. What are the parallel and perpendicular components, respectively, of this force with respect to the ground?

So for the y component it is 110Nsin30 = 55 and the x component is 110Ncos30 = 95. So the components are 55N, 95N

A man pulls a toboggan up a 600m track which is at an angle of 15 degrees with respect to the horizontal. What altitude does it gain?

So it is at an angle. To get the vertical altitude we must use sin. So then it 600sin(15). 600sin(15) = 155.29m as the altitude.

A vehicle designed to operate on a drag strip accelerates from zero to 30 m/s while undergoing a straight path displacement of 45 m. What is the vehicle's acceleration if its value may be assumed to be constant?

So it is constant and we don't know time. The equation utilized will be: V(final)^2 = V(initial)^2 + 2a(displacement or delta x) (30m/s)^2 = 0^2 + 2(a)(45m) 900 m/s = 90m (a) 10 m/s^2 = a

Vector A is 3m long and Vector B is 4m long. The length of the sum of the vectors must be:

So there is two case scenarios: They are both being added (going same direction) or both going opposite direction. Vector A is 3m and Vector B is 4m. In the same direction they add up to 7m. In opposite direction they add up to 1m Therefore the vector must be between 1m and 7m.

A change in a physical quantity w having initial value (wi) and final value (wf) is given by which of the following?

wf - wi

A stone is thrown at an angle of 30° above the horizontal from the top edge of a cliff with an initial speed of 12 m/s. A stop watch measures the stone's trajectory time from top of cliff to bottom to be 5.6 s. How far out from the cliff's edge does the stone travel horizontally? (g = 9.8 m/s2 and air resistance is negligible)

So to find the horizontal displacement, we use cos. So it'll be 12m/s(cos30) = 10.39 m/s. We found the velocity so it is 10.39 m/s * 5.6 seconds = 58.184 m distance traveled.

A student adds two vectors with magnitudes of 200 and 40. Which one of the following is the only possible choice for the magnitude of the resultant?

So two scenarios: same direction or opposite direction - 200 + 40 = 240 - 200 - 40 = 160 So 160 < x < 240

A stone is thrown with an initial speed of 15 m/s at an angle of 53° above the horizontal from the top of a 35 m building. If g = 9.8 m/s2 and air resistance is negligible, then what is the magnitude of the vertical velocity component of the rock as it hits the ground?

So we will find the vertical velocity by using sin. So it is 15m/s(sin53) which equals 11.979 m/s. The equation used is Vf^2 = Vi^2 + 2a(displacement) Vf^2 = 11.98^2 + 2(-9.81m/s^2)(-35) Vf = 28.81

Vector A points north and vector B points east. If C = B - A, then vector C points:

South of east.

Which of the following is not a vector quantity?

Temperature

A strobe photograph of a car moving along a straight road shows the interval between each successive image to be diminishing. If the direction of motion of the car is taken as positive, which of the following are negative?

The average acceleration of the car

A helicopter is traveling at 40m/s at a constant altitude of 100m over a level field. If a wheel falls off the helicopter, with what speed will it hit the ground?

The equation used is V(final)^2 = V(initial)^2 + 2a(displacement or delta x). V(final)^2 = 40m/s + 2(9.81)(100m) V(final) = 60m/s

Arvin the Ant is on a picnic table. He travels 30 cm eastward, then 25 cm northward, and finally 15 cm westward. What is the magnitude of Arvin's net displacement?

The height was 25 cm. Because it traveled 30 east but then went back 15 west, the final placement was 15E. So the net displacement is 15^2 + 25^2 = ? sqrt of 850 = 29.15

A stone is thrown with an initial speed of 15 m/s at an angle of 53° above the horizontal from the top of a 35 m building. If g = 9.8 m/s2 and air resistance is negligible, then what is the magnitude of the horizontal component of velocity as the rock strikes the ground?

The horizontal component of this problem is using cos. So, it is 15cos(53) = 9.027 m/s.

Which of the following is an example of a vector quantity?

Velocity

Curious George throws a banana down with a speed of 15m/s from a tree top. The banana hits the ground after 2.0 s. What is the height of the tree?

We are looking for displacement. The equation utilized is: (x displacement) = V(initial)(time) + 1/2(a)(time)^2 (X displacement) = (15m/s)(2) + 2(9.81m/s^2)(2 seconds)^2 (X displacement) = 49.62 m

A truck moves 70 m east, then moves 120 m west, and finally moves east again a distance of 90 m. If east is chosen as the positive direction, what is the truck's resultant displacement?

West and South is negative. North and East are positive. 70E - 120W + 90E = 40m