Physics questions and solutions

Browse original practice and official past-paper questions. Each question has its own link, with its source and worked solution.

498 questions · Page 16 of 21

1. Q147 · Original practice · 1 mark
   Satellite R has mass $m$ and circular orbital radius $r$. Satellite S has mass $2m$ and circular orbital radius $4r$ about the same planet. What is $T_S/T_R$?
   Gravity and motion
2. Q148 · Original practice · 1 mark
   An electron enters a uniform magnetic field with velocity to the right. The crosses represent a field into the page. What is the initial magnetic force direction?
   Electromagnetism
3. Q149 · Original practice · 1 mark
   An electric charge oscillates and produces an electromagnetic wave in vacuum. Which statement correctly describes the wave?
   Electromagnetism
4. Q150 · Original practice · 1 mark
   Which observer defines an inertial frame over the described interval?
   Special relativity
5. Q151 · Original practice · 1 mark
   A probe travels at $0.70c$ relative to a laboratory and emits simultaneous forward and backward pulses of light in vacuum. Which speeds does the laboratory measure for the two pulses?
   Special relativity
6. Q152 · Original practice · 1 mark
   Monochromatic light has frequency below a clean metal's threshold frequency. Its intensity is increased tenfold while frequency remains constant. Within the usual one-photon photoelectric model, what occurs?
   Quantum theory
7. Q153 · Original practice · 1 mark
   A meson consists of an up quark and an anti-down quark. Up and down quarks have charges $+2e/3$ and $-e/3$, respectively. What are the meson's charge and baryon number?
   The Standard Model
8. Q154 · Original practice · 1 mark
   Which Standard Model interaction is experienced by an electron neutrino, but an electromagnetic interaction is not?
   The Standard Model
9. Q155 · Original practice · 8 marks
   A ball leaves a platform $5.00\,\mathrm m$ above level ground with velocity components $u_x=16.0\,\mathrm{m\,s^{-1}}$ and $u_y=12.0\,\mathrm{m\,s^{-1}}$. A thin wall is $24.0\,\mathrm m$ horizontally from the launch point and $11.0\,\mathrm m$ high. Ignore drag and the ball's size. Use $g=9.8\,\mathrm{m\,s^{-2}}$.
   Gravity and motion
10. Q156 · Original practice · 7 marks
    A camera measures a projectile's position relative to its launch point. At $t=0.500\,\mathrm s$, $(x,y)=(6.00,3.275)\,\mathrm m$. At $t=1.500\,\mathrm s$, $(x,y)=(18.00,2.475)\,\mathrm m$. Ignore air resistance and use $g=9.8\,\mathrm{m\,s^{-2}}$. Positive $y$ is upward.
    Gravity and motion
11. Q157 · Original practice · 6 marks
    A launcher fires from and lands at the same level. Its speed setting is held constant. Measured horizontal ranges have absolute uncertainty $\pm0.2\,\mathrm m$. Ignore drag in the theoretical model. Use $g=9.8\,\mathrm{m\,s^{-2}}$.

    | Launch angle | $20^\circ$ | $35^\circ$ | $55^\circ$ | $70^\circ$ | | --- | --- | --- | --- | --- | | Range (m) | 14.8 | 21.…
    Gravity and motion
12. Q158 · Original practice · 7 marks
    A $5.00\,\mathrm{kg}$ crate is moving up a $30.0^\circ$ incline. A rope pulls parallel to the incline with tension $25.0\,\mathrm N$. Friction has magnitude $4.00\,\mathrm N$. Its initial speed is $3.00\,\mathrm{m\,s^{-1}}$. Use $g=9.8\,\mathrm{m\,s^{-2}}$ and assume the forces remain constant until it first stops.
    Gravity and motion
13. Q159 · Original practice · 6 marks
    A $3.00\,\mathrm{kg}$ block is moving up a $25.0^\circ$ incline. A horizontal force of $15.0\,\mathrm N$ pushes it to the right. Friction of $2.00\,\mathrm N$ acts down the slope. Use $g=9.8\,\mathrm{m\,s^{-2}}$.
    Gravity and motion
14. Q160 · Original practice · 6 marks
    A $0.200\,\mathrm{kg}$ puck co-rotates with a horizontal turntable at radius $0.400\,\mathrm m$. Its period is $1.60\,\mathrm s$. Static friction can supply at most $1.40\,\mathrm N$. Use a model in which friction is the only horizontal force.
    Gravity and motion
15. Q161 · Original practice · 7 marks
    A $0.150\,\mathrm{kg}$ bob moves in a horizontal circle on a string of length $1.20\,\mathrm m$. The string maintains an angle of $30.0^\circ$ to the vertical. Ignore air resistance; use $g=9.8\,\mathrm{m\,s^{-2}}$.
    Gravity and motion
16. Q162 · Original practice · 7 marks
    Four small moons have circular orbits about the same planet. The graph shows $T^2$ against $r^3$, where $r$ is measured from the planet's centre. Treat the fitted line through the origin as exact for this question. Use $G=6.67\times10^{-11}\,\mathrm{N\,m^2\,kg^{-2}}$.
    Gravity and motion
17. Q163 · Original practice · 4 marks
    A planet orbits a star on an ellipse. Its closest and farthest centre-to-centre distances are $2.00\times10^{11}\,\mathrm m$ and $3.00\times10^{11}\,\mathrm m$. Points P and A indicate these positions.
    Gravity and motion
18. Q164 · Original practice · 5 marks
    Two isolated spherical bodies have masses $M$ and $4M$. Their centres are $6.00\times10^7\,\mathrm m$ apart. Consider points on the line between them, outside both bodies. Their radii are small enough that the field-cancellation point is outside each body.
    Gravity and motion
19. Q165 · Original practice · 6 marks
    Two fixed point charges are positioned relative to O: $+2.00\,\mu\mathrm C$ is $0.300\,\mathrm m$ to the left and $-3.00\,\mu\mathrm C$ is $0.400\,\mathrm m$ above. Use $k=9.00\times10^9\,\mathrm{N\,m^2\,C^{-2}}$.
    Electromagnetism
20. Q166 · Original practice · 5 marks
    On the $x$-axis, a fixed charge $+4.00\,\mathrm{nC}$ is at $x=0$ and a fixed charge $-9.00\,\mathrm{nC}$ is at $x=0.500\,\mathrm m$. Consider finite points on this axis, excluding the charge positions.
    Electromagnetism
21. Q167 · Original practice · 5 marks
    A proton starts from rest at electric potential $+200\,\mathrm V$ and moves to a point at $-300\,\mathrm V$. Only the electric force does work. Use $q=+1.60\times10^{-19}\,\mathrm C$ and $m=1.6726219\times10^{-27}\,\mathrm{kg}$.
    Electromagnetism
22. Q168 · Original practice · 6 marks
    Two very long straight wires are perpendicular to the page, $0.120\,\mathrm m$ apart. The left wire carries $8.00\,\mathrm A$ out of the page and the right wire carries $2.00\,\mathrm A$ out of the page. Use $\mu_0=4\pi\times10^{-7}\,\mathrm{T\,m\,A^{-1}}$. Ignore other fields.
    Electromagnetism
23. Q169 · Original practice · 5 marks
    A straight wire has $0.240\,\mathrm m$ of its length in a uniform magnetic field. The angle between current and field is $30.0^\circ$. A force sensor gives readings $F_{\rm raw}$ as current $I$ varies. The fitted graph is shown. Assume the sensor has a constant additive zero offset and the magnetic force is zero at $I=0$.
    Electromagnetism
24. Q170 · Original practice · 6 marks
    Protons enter a velocity selector moving right. A uniform electric field of $2.40\times10^3\,\mathrm{N\,C^{-1}}$ points down the page; a magnetic field of $0.0200\,\mathrm T$ points into the page. Protons that pass straight enter a second region with only a $0.0300\,\mathrm T$ magnetic field into the page. Use $q=1.60\times10^{-19}\,\mathrm C$ and…
    Electromagnetism