Explain why an electromagnet usually has a core of iron or steel

Nova, whose mass is 50kg drops 2 K, what is the amount of heat lost from Nova's body? (specific heat of the human body is 3470 J/kg K)

Why non-metals aren't good at conducting electricity?

Why is the moon tilted

The acceleration due to gravity on the surface of Jupiter is about 2.5 times the acceleration due to gravity on Earth's surface. What would be the weight of a space probe on the surface of Jupiter? A. 2.5 times lighter than on Earth B. 6.

800 joules of work was done lifting a 200 newton box to a shelf directly above the box. How many meters high was the shelf?

What is the main optical element of a refracting telescope?

Two water manometers are connected to a tank of air. One leg of the manometer is open to 100kPa pressure (absolute) while the other leg is subjected to 90kPa. Find the difference in deflection between both manometers, Delta h_a - Delta h_b.

Most geologists believe that the dinosaurs became extinct 65 million years ago when a large comet or asteroid struck the earth, throwing up so much dust that the sun was blocked out for a period of many months. A.

If you drop a silver dollar off a building and it hits the ground in 10 seconds, how fast was the coin going just before it hit?

What is the weight of an with a mass of 32kg