Physics Answers

A wet socks clinging to the inside of a washing machine drum which is spinning at a speed of

4.7 m/s. The radius of the drum is 30 cm.

(a) (Marks: 2) What is the minimum coefficient of static friction

between sock and the drum so that the sock will not slip down?

(b) (Marks: 1) At the same rotational speed and coefficient of

static friction between sock and the drum, would a sock of twice

the mass slide down the wall? Explain your answer.

(c) (Marks: 2) As the drum slows down after the washing is done

at an angular retardation of 3.25 rad/sec2

A particle moves in a straight line such that its displacement, x meters, from a fixed point O

on the line at time t seconds is given by 𝑥 = 60[𝑒

−2𝑡 − 𝑒

−4𝑡

].

(a) Find the time when the particle is instantaneously at rest.

(b) Find the displacement of the particle from O when t = 4 s.

(c) Find the total distance travelled during the first 4 seconds of its motion.

A body is projected at an angle of 30° to the horizontal with a velocity of 150ms^{-1 .} calculate the greatest height (g =10)

a particle is moving along a straight line with the acceleration a= (15 t− 7t^2/3) ft/s^2, where t? is in seconds. determine the velocity and the position of the particle as a function of time when t= 0, v= 0 and x= 15 ft.

What will be the time required to half the amplitude of charge stored by a capacitor and time for the energy stored to be halved in a series LRC circuit with L=41mH, R=0.04 ohms and C=4.7uF?

How much work you need to lift a body of mass 215 kg a distance of 5.65 m using a machine with an efficiency of 72.5%

Gold has a face centered cubic unit cell and has the density 𝟏𝟗. 𝟑 𝒈 𝒄𝒎−𝟑. Calculate the length along an edge. (𝐴𝑢 = 197 𝑔 𝑚𝑜𝑙−1)

How much heat is needed to raise the temperature of 50.0 g of water from 4.5°C to 83.0°C

On a day when the temperature reaches 50c, what is the temperature in degrees F and in Kelvins

In the figure here, a ball is thrown up onto a roof, landing 4.70 s later at height h = 25.0 m above the release level. The ball's path just before landing is angled at θ = 58.0˚ with the roof. (a) Find the horizontal distance d it travels. (Hint: One way is to reverse the motion, as if it is on a video.) What are the (b) magnitude and (c) angle (relative to the horizontal) of the ball's initial velocity?