Physics chapter 5 test

What mass needs to be attached to a spring with a force constant of 7N/m in order to make a simple harmonic oscillator oscillate with a time period of 3s? -0.03kg -1.60kg -30.7kg -63.0kg

1.60 kg

There is a vector A,with magnitude 5 units pointing towards west and vector B,with magnitude 3 units, pointing towards south. Using vector addition, calculate the magnitude of the resultant vector. 4.0 5.8 6.3 8.0

5.8

A mass is hanging from the ceiling with two wires as shown below. Calculate the tension in each wire.

539 N (left wire) and 749 N (right wire)?????!!!

. A person walks 112.0∘ north of west for 55.0m and 63.0∘ south of west for 25.0m. What is the magnitude of his displacement? Solve analytically. -10.84m -65.1m -66.04m -80.00m

66.04m

You walk 33 m to the east, then 60° to your left and walk another 45m. How far are you from where you originally started?

68m???

A large rock is ejected from a volcano with a speed of 30m/s and at an angle 60∘ above the horizontal. The rock strikes the side of the volcano at an altitude of 10.0m lower than its starting point. Calculate the horizontal displacement of the rock. -84.90m -96.59m -169.80m -193.20m

84.90m

A water balloon cannon is fired at 30m/s at an angle of 50∘ above the horizontal. How far away will it fall? -2.35m -3.01m -70.35m -90.44m

90.44m

How or why does a pendulum oscillate? -A pendulum oscillates due to applied force. -A pendulum oscillates due to the elastic nature of the string. -A pendulum oscillates due to restoring force arising from gravity. -A pendulum oscillates due to restoring force arising from tension in the string.

A pendulum oscillates due to restoring force arising from gravity.

A projectile is travelling at 26.0 m/s at an angle of 60.0° above the horizontal at some point in time. What is the horizontal compenent of its velocity? A) 13.0 m/s B) 22.5 m/s C) 24.8 m/s D) 26.0 m/s

A) 13.0 m/s

A vector A has components Ax = 12.0 m and Ay = 5.00 m. What is the angle that vector A makes with the +x-axis? A) 22.6° B) 13.0° C) 67.40 D) 39.5°

A) 22.6°

When Jeff ran up a hill at 7.0 m/s, the horizontal component of his velocity vector was 5.1 m/s. What was the vertical component of Jeff's velocity? A) 4.8 m/s B) 4.3 m/s C) 3.8 m/s D) 3.4 m/s

A) 4.8 m/s

Which of the following statements are true about an obiect in two-dimensional projectile motion with no A) The horizontal acceleration is always zero. B)The acceleration of the object is +g when the object is rising and -g when it is falling. C) The acceleration of the object is zero at its highest point. D) The speed of the object is zero at its highest point.

A) The horizontal acceleration is always zero.

Horizontal and vertical motions of a projectile are independent of each other. What is meant by this? Any object in projectile motion falls at the same rate as an object in free fall, regardless of its horizontal velocity. All objects in projectile motion fall at different rates, regardless of their initial horizontal velocities. Any object in projectile motion falls at the same rate as its initial vertical velocity, regardless of its initial horizontal velocity. All objects in projectile motion fall at different rates and the rate of fall of the object is independent of the initial velocity.

Any object in projectile motion falls at the same rate as an object in free fall, regardless of its horizontal velocity.

A pilot drops a package from a plane flying horizontally at a constant speed. Neglecting air resistance, when the package hits the ground the horizontal location of the plane will A) be behind the package. B) be directly over the package C) be in front of the package. D) depend on the speed of the plane when the package was released.

B) be directly over the package

For general projectile motion with no air resistance, the horizontal component of a projectile's velocity A) remains zero. B) remains a non-zero constant. C) continuously increases. D) continuously decreases.

B) remains a non-zero constant.

A player kicks a soccor ball in a high are toward the opponent's goal. At the highest point in it trajectory, A) the horizontal velocity is zero. B) the vertical velocity is zero. C) the ball's acceleration is zero. D) the ball's acceleration points upward.

B) the vertical velocity is zero.

The x component of vector A is 8.7 units, and its y component is -6.5 units. The magnitude of A is closest to A) 9.9 units B) 7.9 units C)8.9 units D) 11 units

D) 11 units

Three forces act on an object. One force is 10 N to the right, one force 3 N downwards, and one force is 12 N at an angle of 30° above the horizontal, as shown in the diagram below. What is the net force (magnitude and direction) on the object?

Ef=√20.4^2 +3^2 = 10.8 N 0?=tan^-1 (3/20.4) = 8°

Chapter 5 quiz

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Key terms from textbook

!!!!!

What is the time period of a 6cm long pendulum on earth? -0.08s -0.49s -4.9s -80s

0.49s

What is the restoring force? -The normal force on the surface of an object -The weight of a mass attached to an object -Force which is applied to deform an object from its original shape -Force which brings an object back to its equilibrium position

Force which brings an object back to its equilibrium position

Vector intro packet

go do this packet!

Forces 2d worksheet

need to have key when studying this one!

textbook

read all of chapter 5

When will the x-component of a vector with angle 𝜃θ be greater than its y-component? -0∘<θ<45∘ -θ=45∘ -45∘<θ<60∘ -60∘<θ<90∘

0∘<θ<45∘

A stationary block has three forces acting on it: a 20 N force to the right, a 15 N force downwards, and a third force, R of unknown magnitude and direction, as shown in the following diagram:

20+Rx=0 Rx=-20 15-Ry=0 Ry=15 R=√(-20)^2+15^2 = 25N 0?=tan^-1(15/20) = 37° above -x direction (or 143°)

A ball is thrown in the air at an angle of 40°. If the maximum height it reaches is 10 m, what must be its initial speed? -17.46 m/s -21.78 m/s -304.92 m/s -474.37 m/s

21.78 m/s

A Projectile is launched from ground level at an angle of 40°. If it strikes the ground 50 m away from where it was launched, What was its initial velocity? What is the maximum height that it reached?

22.3 m/s 21 m

A person wants to fire a water balloon cannon such that it hits a target 100 m away. If the cannon can only be launched at 45° above the horizontal, what should be the initial speed at which it is launched? -31.3 m/s -37.2 m/s -980.0 m/s -1,385.9 m/s

31.3 m/s

What is the magnitude of a vector whose x-component is 2units and whose angle is 60∘? 1.0units 2.0units 2.3units 4.0units

4.0 units

A simple harmonic oscillator has time period 4s. If the mass of the system is 2kg, what is the force constant of the spring used? -0.125N/m -0.202N/m -0.81N/m -4.93N/m

4.93N/m

What is the optimum angle at which a projectile should be launched in order to cover the maximum distance? -0∘ -45∘ -60∘ -90∘

45∘

Two people pull on ropes tied to a trolley, each applying 44 N of force. The angle the ropes form with each other is 39.5°. What is the magnitude of the net force exerted on the trolley? -0.0 N -79.6 N -82.8 N -88.0 N

82.8 N

A car travels 20 km west and then 20km south. What is the magnitude of its displacement vector? -0km -20km -28km -40km

?

For an object in simple harmonic motion, when does the maximum speed occur? -At the extreme positions -At the equilibrium position -At the moment when the applied force is removed -Midway between the extreme and equilibrium positions

At the equilibrium position

In an air-free chamber, a pebble is thrown horizontally, and at the same instant a second pebble is dropped from the same height. Compare the times of fall of the two pebbles. A) The thrown pebble hits the ground first. B) The dropped pebble hits the ground first. C) They hit the ground at the same time. D) We cannot tell without knowing which pebble is heav

C) They hit the ground at the same time.

For a given oscillator, what are the factors that affect its period and frequency? -Mass only -Force constant only -Applied force and mass -Mass and force constant

Mass and force constant

Two springs are attached to two hooks. Spring A has a greater force constant than spring B. Equal weights are suspended from both. Which of the following statements is true? -Spring A will have more extension than spring B. -Spring B will have more extension than spring A. -Both springs will have equal extension. -Both springs are equally stiff.

Spring B will have more extension than spring A.

With reference to simple harmonic motion, what is the equilibrium position? -The position where velocity is the minimum -The position where the displacement is maximum -The position where the restoring force is the maximum -The position where the object rests in the absence of force

The position where the object rests in the absence of force

2D Force Examples (slides)

go review slides

More 2D practice

go to schoology and do both practice

Horizontal Projectile Hw

go to schoology and do this

simple harmonic motion

go to textbook and do problems on 5.5

True or False—A person is following a set of directions. He has to walk 2 km east and then 1 km north. He takes a wrong turn and walks in the opposite direction for the second leg of the trip. The magnitude of his total displacement will be the same as it would have been had he followed directions correctly. True False

true

Two identical items, object 1 and object 2, are dropped from the top of a 50.0m building. Object 1 is dropped with an initial velocity of 0m/s, while object 2 is thrown straight downward with an initial velocity of 13.0m/s. What is the difference in time, in seconds rounded to the nearest tenth, between when the two objects hit the ground? -Object 1 will hit the ground 3.2s after object 2. -Object 1 will hit the ground 2.1s after object 2. -Object 1 will hit the ground at the same time as object 2. -Object 1 will hit the ground 1.1s after object 2.

Object 1 will hit the ground 1.1s after object 2.

What is Hooke's law? -Restoring force is directly proportional to the displacement from the mean position and acts in the the opposite direction of the displacement. -Restoring force is directly proportional to the displacement from the mean position and acts in the same direction as the displacement. -Restoring force is directly proportional to the square of the displacement from the mean position and acts in the opposite direction of the displacement. -Restoring force is directly proportional to the square of the displacement from the mean position and acts in the same direction as the displacement.

Restoring force is directly proportional to the displacement from the mean position and acts in the the opposite direction of the displacement.

A person walks 10.0 m north and then 2.00 m east. Solving analytically, what is the resultant displacement of the person? -R→ = 10.2 m, θ = 78.7º east of north -R→ = 10.2 m, θ = 78.7º north of east -R→ = 12.0 m, θ = 78.7º east of north -R→ = 12.0 m, θ = 78.7º north of east

R→ = 10.2 m, θ = 78.7º north of east

Construct a seconds pendulum (pendulum with time period 2 seconds).

T=2pie√l/g l=T^2g/4pie^2 l=(2s)^2(9.8m/s^2) divided 4pie^2 l=1m

Two simple harmonic oscillators are constructed by attaching similar objects to two different springs. The force constant of the spring on the left is 5N/m and that of the spring on the right is 4N/m. If the same force is applied to both, which of the following statements is true? -The spring on the left will oscillate faster than spring on the right. -The spring on the right will oscillate faster than the spring on the left. -Both the springs will oscillate at the same rate. -The rate of oscillation is independent of the force constant.

The spring on the left will oscillate faster than spring on the right.

. Ignoring drag, what is the x-component of the acceleration of a projectile? Why? -The x-component of the acceleration of a projectile is 00 because acceleration of a projectile is due to gravity, which acts in the y direction. -The x component of the acceleration of a projectile is 𝑔g because acceleration of a projectile is due to gravity, which acts in the x direction. -The x-component of the acceleration of a projectile is 00 because acceleration of a projectile is due to gravity, which acts in the x direction. -The x-component of the acceleration of a projectile is 𝑔g because acceleration of a projectile is due to gravity, which acts in the y direction.

The x-component of the acceleration of a projectile is 00 because acceleration of a projectile is due to gravity, which acts in the y direction.

After a projectile is launched in the air, in which direction does it experience constant, non-zero acceleration, ignoring air resistance? -The x direction -The y direction -Both the x and y directions -Neither direction

The y direction

What is the equilibrium position of a pendulum? -When the tension in the string is zero -When the pendulum is hanging straight down -When the tension in the string is maximum -When the weight of the mass attached is minimum

When the pendulum is hanging straight down

A 1.2 kg ball tied to a string fixed to the ceiling is pulled to one side by a force F. a) Find the force needed to hold the ball at this position. b) Find the tension force in the string

a) F-T cos60°=0 F=13.9 cos60°=6.9 N b) Tsin60°-12=0 T=12/sin60° = 13.9N

Which is true when the height of a projectile is at its maximum? -vy=0 -vy=maximum -vx=maximum

vy=0

Using the conventional choice for positive and negative axes described in the text, what is the y-component of the acceleration of an object experiencing projectile motion? −9.8m/s −9.8m/s2 9.8m/s 9.8m/s2

−9.8m/s2

As shown in the figure, a heavy rock is shot upward form the deg pf a vertical cliff. It leaves the edge of the cliff with an initial velocity of 15 m/s directed at 25° above the horizontal. How high is the cliff?

△x=3.4 Vox=15 cos25=13.595 ay=0 b=? △y=? Voy=15sin25=6.339 ay=-9.8 b=? △y=6.339(0.25)+1/2(-9.8)(0.23)^2 △y=1.585-0.306 △y=-1.279 3.4=13.595b+1/20b^2 3.4=13.595b =0.25 b=0.25 △y=-1.279

A projectile is shot horizontally at 23.4m/s from the roof of a building 55m tall. a) determine the time nesscary for the projectile to reach the ground below. b) determine the distance form the base of the building that the projectile lands

△y=v*b+1/2ab^2 △y=-55 Voy=0 ay=9.8 b=? -55=vb+1/2(-9.8)b^2 -55=-4.9b^2 b^2=11.2 △x=v*b+1/2ab^2 △x=? Vox=23.4 ax=0 b=? △x=23.4(11.224)+1/2(0)(125.44) △x=262.65m

The resultant vector of the addition of vectors a→ and b→ is r→. The magnitudes of a→, b→, and r→ are 𝐴, 𝐵, and 𝑅, respectively. Which of the following is true? -𝑅𝑥+𝑅𝑦=0 -𝐴𝑥+𝐴𝑦=A→ -𝐴𝑥+𝐵𝑦=𝐵𝑥+𝐴𝑦 -𝐴𝑥+𝐵𝑥=𝑅𝑥

𝐴𝑥+𝐵𝑥=𝑅𝑥

How can we express the x and y-components of a vector in terms of its magnitude, 𝐴A, and direction, global angle 𝜃θ? 𝐴𝑥=𝐴cos𝜃Ax=Acos⁡θ;𝐴𝑦=𝐴sin𝜃Ay=Asin⁡θ 𝐴𝑥=𝐴cos𝜃Ax=Acos⁡θ;𝐴𝑦=𝐴cos𝜃Ay=Acos⁡θ 𝐴𝑥=𝐴sin𝜃Ax=Asin⁡θ;𝐴𝑦=𝐴cos𝜃Ay=Acos⁡θ 𝐴𝑥=𝐴sin𝜃Ax=Asin⁡θ;𝐴𝑦=𝐴sin𝜃Ay=Asin⁡θ

𝐴𝑥=𝐴cos𝜃Ax=Acos⁡θ; 𝐴𝑦=𝐴cos𝜃

. If a pendulum from earth is taken to the moon, will its frequency increase or decrease? Why? -It will increase because 𝑔g on the Moon is less than 𝑔g on Earth. -It will decrease because 𝑔g on the Moon is less than 𝑔g on Earth. -It will increase because 𝑔g on the Moon is greater than 𝑔g on Earth. -It will decrease because 𝑔g on the Moon is greater than 𝑔g on Earth.

It will decrease because 𝑔g on the Moon is less than 𝑔g on Earth.

Two vectors are equal in magnitude and opposite in direction. What is the magnitude of their resultant vector? The magnitude of the resultant vector will be zero. The magnitude of the resultant vector will be twice the magnitude of the original vector. The magnitude of the resultant vector will be same as magnitude of the original vector. The magnitude of the resultant vector will be half the magnitude of the original vector.

The magnitude of the resultant vector will be zero.

Why is there a negative sign in the equation for Hooke's law? - The negative sign indicates that displacement decreases with increasing force. - The negative sign indicates that the direction of the applied force is opposite to that of displacement. - The negative sign indicates that the direction of the restoring force is opposite to that of displacement. - The negative sign indicates that the force constant must be negative.

The negative sign indicates that the direction of the restoring force is opposite to that of displacement.

A 43.0 kg sign is suspended by two wires, as the drawing shows. a) Draw a FBD for the sign. b) Find the tension in wire 1 and in wire 2.

a) check answer key! b) -T cos(55°) +T2cos(72°)=0 T sin(55°) +T2sin(72°)-430=0 T1=166N T2=309N