AP Physics

Unit 4 - Energy

Intermediate

Mathematical

FRQ

You're a Pro Member

Supercharge UBQ

0 attempts

0% avg

UBQ Credits

Verfied Answer
Verfied Explanation 0 likes
0
Step Derivation/Formula Reasoning
(a) Accelerarion of the particle when its displacement is 6 m
1 \[F = ma\] Newton’s second law relates force \( F \), mass \( m \), and acceleration \( a \).
2 \[a = \frac{F}{m}\] Rearrange the formula to solve for acceleration.
3 \[a = \frac{4\, \text{N}}{0.20\, \text{kg}}\] Substitute the force from the graph (4 N) and the mass (0.20 kg).
4 \[a = 20\, \text{m/s}^2\] Calculate the acceleration.
(b) Time taken for the object to be displaced the first 12 m
1 \[\Delta x = v_i t + \frac{1}{2} a t^2\] Using the kinematic equation with initial velocity \( v_i = 0 \).
2 \[12 = \frac{1}{2} \cdot 20 \cdot t^2\] Substitute \( \Delta x = 12 \) m and \( a = 20 \text{ m/s}^2 \).
3 \[12 = 10 t^2\] Simplify the equation.
4 \[t^2 = 1.2\] Divide both sides by 10.
5 \[t = \sqrt{1.2}\] Solve for \( t \).
6 \[t \approx 1.095\, \text{s}\] Calculate the time taken.
(c) The amount of work done by the net force in displacing the object the first 12 m
1 \[W = F \Delta x\] Work done \( W \) is the product of force and displacement.
2 \[W = 4 \times 12\] Substitute \( F = 4 \text{ N} \) and \( \Delta x = 12 \text{ m} \).
3 \[W = 48 \text{ J}\] Calculate the work done.
(d) The speed of the object at displacement \( x = 12 \text{ m} \)
1 \[v_x^2 = v_i^2 + 2a \Delta x\] Use the kinematic equation with initial velocity \( v_i = 0 \).
2 \[v_x^2 = 0 + 2 \cdot 20 \cdot 12\] Substitute \( a = 20 \text{ m/s}^2 \) and \( \Delta x = 12 \text{ m} \).
3 \[v_x^2 = 480\] Calculate \( v_x^2 \).
4 \[v_x = \sqrt{480}\] Solve for \( v_x \).
5 \[v_x \approx 21.9 \, \text{m/s}\] Calculate the velocity.
(e) The final speed of the object at displacement \( x = 20 \text{ m} \)
1 \[W_{total} = W_{1} + W_{2}\] Calculate total work done by summing areas under the \( F \) vs. \( x \) graph.
2 \[W_{1} = F_{1} \times \Delta x_{1} = 4 \times 12 = 48 \, \text{J}\] The work done on the first section (rectangle 0 to 12 m).
3 \[W_{2} = \frac{1}{2} \cdot 4 \cdot 8 = 16 \, \text{J}\] The work done on the second section (triangular area from 12 m to 20 m).
4 \[W_{total} = 48 + 16 = 64 \, \text{J}\] Total work done.
5 \[\text{K.E.} = \frac{1}{2}m v_x^2\] Relate total work done to kinetic energy gain.
6 \[64 = \frac{1}{2} \cdot 0.20 \cdot v_x^2\] Substitute \( m = 0.20 \, \text{kg} \).
7 \[v_x^2 = 640\] Solve for \( v_x^2 \).
8 \[v_x = \sqrt{640}\] Solve for \( v_x \).
9 \[\boxed{v_x \approx 25.3 \, \text{m/s}}\] Calculate the final speed at \( x = 20 \text{ m} \).

Need Help? Ask Phy To Explain

Just ask: "Help me solve this problem."

Just Drag and Drop!
Quick Actions ?
×

Topics in this question

Join 1-to-1 Elite Tutoring

See how Others Did on this question | Coming Soon

Discussion Threads

Leave a Reply

  1. \(20 \, \text{m/s}^2\)
  2. \(1.095 \, \text{s}\)
  3. \(48 \, \text{J}\)
  4. \(21.9 \, \text{m/s}\)
  5. \(\boxed{25.3 \, \text{m/s}}\)

Nerd Notes

Discover the world's best Physics resources

Continue with

By continuing you (1) agree to our Terms of Sale and Terms of Use and (2) consent to sharing your IP and browser information used by this site’s security protocols as outlined in our Privacy Policy.

Error Report

Sign in before submitting feedback.

Sign In to View Your Questions

Share This Question

Enjoying UBQ? Share the 🔗 with friends!

Link Copied!
KinematicsForces
\(\Delta x = v_i t + \frac{1}{2} at^2\)\(F = ma\)
\(v = v_i + at\)\(F_g = \frac{G m_1 m_2}{r^2}\)
\(v^2 = v_i^2 + 2a \Delta x\)\(f = \mu N\)
\(\Delta x = \frac{v_i + v}{2} t\)\(F_s =-kx\)
\(v^2 = v_f^2 \,-\, 2a \Delta x\) 
Circular MotionEnergy
\(F_c = \frac{mv^2}{r}\)\(KE = \frac{1}{2} mv^2\)
\(a_c = \frac{v^2}{r}\)\(PE = mgh\)
\(T = 2\pi \sqrt{\frac{r}{g}}\)\(KE_i + PE_i = KE_f + PE_f\)
 \(W = Fd \cos\theta\)
MomentumTorque and Rotations
\(p = mv\)\(\tau = r \cdot F \cdot \sin(\theta)\)
\(J = \Delta p\)\(I = \sum mr^2\)
\(p_i = p_f\)\(L = I \cdot \omega\)
Simple Harmonic MotionFluids
\(F = -kx\)\(P = \frac{F}{A}\)
\(T = 2\pi \sqrt{\frac{l}{g}}\)\(P_{\text{total}} = P_{\text{atm}} + \rho gh\)
\(T = 2\pi \sqrt{\frac{m}{k}}\)\(Q = Av\)
\(x(t) = A \cos(\omega t + \phi)\)\(F_b = \rho V g\)
\(a = -\omega^2 x\)\(A_1v_1 = A_2v_2\)
ConstantDescription
[katex]g[/katex]Acceleration due to gravity, typically [katex]9.8 , \text{m/s}^2[/katex] on Earth’s surface
[katex]G[/katex]Universal Gravitational Constant, [katex]6.674 \times 10^{-11} , \text{N} \cdot \text{m}^2/\text{kg}^2[/katex]
[katex]\mu_k[/katex] and [katex]\mu_s[/katex]Coefficients of kinetic ([katex]\mu_k[/katex]) and static ([katex]\mu_s[/katex]) friction, dimensionless. Static friction ([katex]\mu_s[/katex]) is usually greater than kinetic friction ([katex]\mu_k[/katex]) as it resists the start of motion.
[katex]k[/katex]Spring constant, in [katex]\text{N/m}[/katex]
[katex] M_E = 5.972 \times 10^{24} , \text{kg} [/katex]Mass of the Earth
[katex] M_M = 7.348 \times 10^{22} , \text{kg} [/katex]Mass of the Moon
[katex] M_M = 1.989 \times 10^{30} , \text{kg} [/katex]Mass of the Sun
VariableSI Unit
[katex]s[/katex] (Displacement)[katex]\text{meters (m)}[/katex]
[katex]v[/katex] (Velocity)[katex]\text{meters per second (m/s)}[/katex]
[katex]a[/katex] (Acceleration)[katex]\text{meters per second squared (m/s}^2\text{)}[/katex]
[katex]t[/katex] (Time)[katex]\text{seconds (s)}[/katex]
[katex]m[/katex] (Mass)[katex]\text{kilograms (kg)}[/katex]
VariableDerived SI Unit
[katex]F[/katex] (Force)[katex]\text{newtons (N)}[/katex]
[katex]E[/katex], [katex]PE[/katex], [katex]KE[/katex] (Energy, Potential Energy, Kinetic Energy)[katex]\text{joules (J)}[/katex]
[katex]P[/katex] (Power)[katex]\text{watts (W)}[/katex]
[katex]p[/katex] (Momentum)[katex]\text{kilogram meters per second (kgm/s)}[/katex]
[katex]\omega[/katex] (Angular Velocity)[katex]\text{radians per second (rad/s)}[/katex]
[katex]\tau[/katex] (Torque)[katex]\text{newton meters (Nm)}[/katex]
[katex]I[/katex] (Moment of Inertia)[katex]\text{kilogram meter squared (kgm}^2\text{)}[/katex]
[katex]f[/katex] (Frequency)[katex]\text{hertz (Hz)}[/katex]

General Metric Conversion Chart

Example of using unit analysis: Convert 5 kilometers to millimeters. 

  1. Start with the given measurement: [katex]\text{5 km}[/katex]

  2. Use the conversion factors for kilometers to meters and meters to millimeters: [katex]\text{5 km} \times \frac{10^3 \, \text{m}}{1 \, \text{km}} \times \frac{10^3 \, \text{mm}}{1 \, \text{m}}[/katex]

  3. Perform the multiplication: [katex]\text{5 km} \times \frac{10^3 \, \text{m}}{1 \, \text{km}} \times \frac{10^3 \, \text{mm}}{1 \, \text{m}} = 5 \times 10^3 \times 10^3 \, \text{mm}[/katex]

  4. Simplify to get the final answer: [katex]\boxed{5 \times 10^6 \, \text{mm}}[/katex]

Prefix

Symbol

Power of Ten

Equivalent

Pico-

p

[katex]10^{-12}[/katex]

Nano-

n

[katex]10^{-9}[/katex]

Micro-

µ

[katex]10^{-6}[/katex]

Milli-

m

[katex]10^{-3}[/katex]

Centi-

c

[katex]10^{-2}[/katex]

Deci-

d

[katex]10^{-1}[/katex]

(Base unit)

[katex]10^{0}[/katex]

Deca- or Deka-

da

[katex]10^{1}[/katex]

Hecto-

h

[katex]10^{2}[/katex]

Kilo-

k

[katex]10^{3}[/katex]

Mega-

M

[katex]10^{6}[/katex]

Giga-

G

[katex]10^{9}[/katex]

Tera-

T

[katex]10^{12}[/katex]

  1. 1. Some answers may vary by 1% due to rounding.
  2. Gravity values may differ: \(9.81 \, \text{m/s}^2\) or \(10 \, \text{m/s}^2\).
  3. Variables can be written differently. For example, initial velocity (\(v_i\)) may be \(u\), and displacement (\(\Delta x\)) may be \(s\).
  4. Bookmark questions you can’t solve to revisit them later
  5. 5. Seek help if you’re stuck. The sooner you understand, the better your chances on tests.

Phy Pro

The most advanced version of Phy. 50% off, for early supporters. Prices increase soon.

$11.99

per month

Billed Monthly. Cancel Anytime.

Trial  –>  Phy Pro

You can close this ad in 5 seconds.

Ads show frequently. Upgrade to Phy Pro to remove ads.

You can close this ad in 7 seconds.

Ads display every few minutes. Upgrade to Phy Pro to remove ads.

You can close this ad in 5 seconds.

Ads show frequently. Upgrade to Phy Pro to remove ads.

Jason here! Feeling uneasy about your next physics test? We will help boost your grade in just two hours.

We use site cookies to improve your experience. By continuing to browse on this website, you accept the use of cookies as outlined in our privacy policy.