Physics Answers

Two point charges separated by a distance of 30cm in air. One of the charges is positive and has a magnitude of 10 micro coulombs and the other is a negative charge of magnitude 15 micro coulombs. Calculate the force between the charges, state if it is force of attraction or repulsion

The concentrated charges of 0.25microcoulombs each are located at the vertices of an equilateral triangle of 10cm side. Find the magnitude and direction of force on one charge due to other charges

The coefficient of linear expansion of steel is  

12 × 10^-6/C°. A railroad track is made of individual rails of steel 1.0 km in length. By what length would these rails change between a cold day when the temperature is –10 °C and a hot day at 30 °C?

how much heat must be absorbed by 475 grams of water to raise its temperature by 30°c

Ellen throws a ball toward a wall at speed 30.0 m/s and at angle 45.0° above the

horizontal. The wall is distance 25.0 m from the release point of the ball.

a) (5%) How far above the release point does the ball hit the wall?

b) (5%) What is the horizontal component of its velocity as it hits the wall?

c)

(5%) What is the vertical component of its velocity as it hits the wall?

d

(5%) When it hits, has it passed the highest point on its trajectory?

An 85 kg person is parachuting and experiencing a downward acceleration of 4.5 m/s2. The

mass of the parachute is 4.0 kg.

a) (10%) Draw free body diagram.

b) (10%) What is the upward force on the open parachute from the air?

C)

(10%) What is the downward force on the parachute from the person?

2. The ball is tied to a string to whirl it having a radius of 50 cm at a velocity

of 1.2 m/s. What will be the acceleration of the ball?

vector has y components ay= 13.0m

10.We want to slide a 12-kg box up a 2.5-m-long ramp inclined at

. A worker,

ignoring friction, calculates that he can do this by giving it an initial speed of 5 m/s

at the bottom and letting it go. But friction is not negligible; the box slides only 1.6

m up the ramp, stops, and slides back down.

a. Find the magnitude of the friction force acting on the crate, assuming that it is

constant.

A force of 20N pulls two carts tied together with a string. The carts 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.