Physics Answers

A girl is pressing a 2kg book against a vertical wall. If the coefficient of friction between the book and the wall is 0.30, how hard should the girl push to allow the book to slide down the wall at constant speed?

Please show the complete solution.

A force of 20N pulls two carts tied together with a string. The carat with masses 3kg and 4kg, respectively, run on a smooth level surface. Find :

a. The acceleration of the 4kg cart

b. The acceleration of the 3kg cart

c. The tension on the string connecting the two carts.

A block of mass 5.00 kg rests on a horizontal surface where the coefficient of kinetic friction between the two is 0.200. A string attached to the block is pulled horizontally, resulting in a 3.00 m/s² acceleration by the block. Find the tension in the string. (g = 9.80 m/s²)

A violin string 15.0cm long and fixed at both ends oscillates in its n=1 mode. The

speed of waves on the string is 250ms-1 and the speed of sound in air is 348ms-1. Find,

(i)the frequency of the waves

(ii)the wavelength of the emitted sound.

(b)A closed organ pipe 60cm long and of cross-sectional area 50cm2 is resonating at its

fundamental frequency. If the amplitude of the air at the open end is 0.20cm, find the

acoustic power radiated.

(c)A plane sound wave traveling through air has maximum acoustic pressure

of 10-2Nm-2. If the speed of sound is 343ms-1, and the density is 1.29kgm-3, find the

average kinetic energy density of the gas.

A source of sound wave produces waves in air of wavelength 1.65,if the speed of sound in air is 330ms-¹ the period of vibration in second is?

A sports car must achieve a velocity of 100m/s after passing the entry tollgate of an expressway. If it can do this after traveling 1km, what must it's acceleration ve?

How far is point P from a proton if the electric potential at point P is +180 V?

. You joined a “dogsled” race during your winter break. To start, you

pulled the sled (total mass of 85 kg) with a force of 650N at 50° above

the horizontal. Find the work done on the sled after it moves at a

distance of 800cm. (Round to 2 decimal places)

A metal bar that has a cross-sectional area of 4,0 cm² and length of 50.0 cm is stretched by a force of 1.0x10⁴ N.

i) Find the stress on the wire.

ii) If the bar elongates by 0.5 cm, what is the strain in the wire?

iii) Determine the Young’s Modulus of the wire.

iv) Calculate the strain energy per unit volume stored in the wire.

A stone is thrown straight downward with initial speed 8.0 m/s from a height of 25 m. Find (a) the time it takes to reach the ground and (b) the speed with which it strikes.