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A stone is thrown horizontally at 5m/s from a platform 10m above ground. Find time till impact with ground.

Use SUVAT for constant vertical acceleration. Solve for t. S = -10U = 0V = -A = -gT = tS=UT+(AT^2)/2t = sqrt(20/g)
MH
Answered by Mathew H. • Physics tutor
2053 Views

Why is the classical model of light insufficient in explaining the photoelectric effect?

In the classical model, light is a wave and it's energy depends on its intensity. This would predict electron emission at all wavelengths of light. So the model cannot explain the threshold frequency of ligh...
RK
Answered by Roy K. • Physics tutor
5619 Views

An exo-planet orbits its local star, of mass 2.00x10^30kg, in a steady circular orbit of radius 8.00x10^8km. Calculate the orbital period of the star, in years.

Key idea is equating gravitational force between planet and star (right hand side) with the centripetal force necessary to maintain the orbit (left hand side): ( mv 2 )/r = (GMm)/r 2 Notice how the mass of t...
Answered by • Physics tutor
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Discuss how the graph of orbital velocities in rotational galaxies against distance from the galactic centre implies the existence of dark matter.

Within the central swell of the galaxy, we can see that the orbital velocity increases almost linearly with distance, which corresponds with the formula for orbital velocity (namely that v=sqrt(GM/r)), as wi...
JT
Answered by Jack T. • Physics tutor
2000 Views

What is the difference between distance and displacement?

Let us have an object that starts at an origin point O and ends at some finishing point F. Distance is the total length of the path taken by the object between O and F, this is also known from our everyday l...
GM
Answered by Greg M. • Physics tutor
2096 Views