Physics Answers

A plane which is flying horizontally at a constant speed Vo and at a height h above the sea must drop a bundle of supplies to a castaway on a small raft. Write down newtons second law for the bundle as it falls from the plane, assuming you can neglect air resistance.

A projectile is fired at an angle of 30° above the horizontal from the edge of a vertical cliff. Ignore

air resistance. (a) Is the projectile’s velocity ever only horizontal? If so, when; if not, why not?

(b) Is its velocity ever only vertical? If so, when; if not, why not? (c) Are there any points at which

the projectile’s acceleration is either parallel or perpendicular to its velocity? Explain.

if the change in resistance of copper wire on stretching is 4%, then its length is stretched by

What is the magnitude of the electric force between two electrons

separated by a distance of 0.10 nm? (1 nm = 1 x 10 -9 m)

Two charges, a= +6uC and qz=-5uC.

are separated by a distance r = 15cm.

What is the magnitude of the electric

force? Is the force repulsive or attractive?

The edge of a cube was found to be 1.50 plus or minus 0.05 what is its surface area and its volume.

When a 12.0 car battery power a single 30.0w headlight how many electrons pass through it each second

A 36-ohm resistor is connected in parallel with an unknown resistor R. Their combination is then connected in series with a 12-ohm resistor. Find the value of R such that power drawn by the parallel combination of 36 ohms and R is equal to the power in the 12-ohm resistor.

Your mother is using an electric flat iron that draws a current of 15 A when connected to a 220 V line.

(a) What is the resistance of the heating element of the flat iron assuming that it obeys Ohm’s law? What is the resistivity of the heating element if it is a wire that is 2.7 cm long with a cross-sectional area of 2.1 x 10^-4 m²?

A compound gear train has a 30tooth driver gear A, machine with a 90tooth follower gear B, mounted on thesame shaft as Band attached to it's gear Cwith 60 teeth, machine with a gear D on the output shaft having 120teeth. Calculate the velocity ratio and mechanical advantage if the overall efficiency is 72%