Physics Answers

a. A transformer is used to change the 230 volt mains electricity supply to the 12 volts

needed to operate a low voltage halogen lamp. The current through the halogen lamp

is 4 amps. Assuming that the transformer is 100 % efficient determine the:

ii. number of turns on the primary coil if there are 200 turns on the secondary.

iii. power output of the transformer.

b. A metallic conductor of length 0.40m carrying a current of 5 A experiences a 

Force of 26N in a magnetic field of strength 15 T. Determine the angle between 

the current in the conductor and the magnetic field. 

a. A transformer is used to change the 230 volt mains electricity supply to the 12 volts

needed to operate a low voltage halogen lamp. The current through the halogen lamp

is 4 amps. Assuming that the transformer is 100 % efficient determine the:

i. current drawn by the transformer from the mains electricity supply.

An electric device is designed to dissipate 990 W of power when connected to a 110 V source. Compute: current drawn

If a 900.0 kg sports car slows to 15.0 m/s to check out an accident scene and the 1500.0 kg pick up behind him continues traveling at 35.0 m/s, with what velocity will the two move if they lock bumpers after a rear-end collision?

Mark, a 65.0 kg skin diver, shoots a 4.0 kg spear with a speed of 25 m/s at fish who darts quickly away without getting hit. How fast does Mark move backwards when the spear is shot?

Mira and her twin sister Joy have a combined mass of 250.0 kg and are zooming along in a 150.0 kg amusement park bumper car at 15.0 m/s. They bump Miguel`s car, which is sitting still. Miguel has a mass of 45.0 kg. After the elastic collision, the twins continue ahead with a speed of 6.12 m/s. How fast is Miguel`s car bumped across the floor?

The acceleration of a point is a= 20t m/s2. When t= 0, x= 40 m and v= - 10 m/s. What are the position and velocity at t= 3 s?

The position of a point is given as a function of time by x= 4t − 6t + 2t− 1 , where x and t are expressed in meters and seconds. Determine the position, the velocity, and the acceleration of the particle when t= 2 s.

A lift, mass 250 kg, is initially at rest on the ground floor of a tall building. Passengers with an unknown total mass, m, climb into the lift. The lift accelerates upwards at 1.6 m/s−2. The cable supporting the lift exerts a constant upward force of 7700 N. Use g = 10 m/s−2. 

1. Draw a labeled force diagram indicating all the forces acting on the lift while it accelerates upwards.

2. What is the maximum mass, m, of the passengers the lift can carry in order to achieve a constant upward acceleration of 1.6 m/s−2.

The coefficient of static and kinetic frictions between a 3.0-kg box and a desk are 0.40 and 0.30, respectively. What is the net force on the box when a 14.3 N horizontal force is applied to the box?