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Questions in physics

[Done] Which event signals the birth of a star? A. A core shrinks and explodes in a supernova. B. A protostar collapses, becoming dense and hot. C. Extreme heat and pressure causes nuclear fusion. D. A mass of gas and dust grows and forms a protostar.

[Done] Select the best answer for the question. Which force is responsible for pulling a plate downward into the asthenosphere? A. Magnetism B. Gravity C. Air pressure D. Buoyancy

[Done] Which object forms when a supergiant explodes? A. a red giant B. a protostar C. a white dwarf D. a neutron star

[Done] What is the term for producing a current by moving a wire through a magnetic field? solenoid induction flowing induction electromagnetic induction coiled induction

[Done] A 5 kg weight is accelerated from rest to [tex]$20 m / s$[/tex] in 2 seconds. What is the force acting on the body?

[Done] How do spectrographs help astronomers classify stars? A. They determine the size of stars. B. They evaluate the color of stars. C. They measure the brightness of stars. D. They analyze the composition of stars.

[Done] An electric device delivers a current of [tex]$15.0 A$[/tex] for 30 seconds. How many electrons flow through it?

[Done] Two particles have position vectors given by: [tex]\begin{array}{l} \overrightarrow{r_1}=2 t i-t^2 j+\left(3 t^2-4 t\right) k \\ \overrightarrow{r_2}=(5 t-12 t+4) i+t^3 j-3 t k \end{array}[/tex] Express in vector form, the relative velocity of the 2nd particle with respect to the 1st particle.

[Done] An electric device delivers a current of [tex]$15.0 A$[/tex] for 30 seconds. How many electrons flow through it?

[Done] What would make oppositely charged objects attract each other more? A. increasing the positive charge of the positively charged object and increasing the negative charge of the negatively charged object B. decreasing the positive charge of the positively charged object and decreasing the negative charge of the C. increasing the distance between the positively charged object and the negatively charged object D. maintaining the distance between the positively charged object and the negatively charged object