What is constant: Mass of a body or weight of a body

What was the first instrument to ever record an earthquake?

The velocity of a car traveling in a straight line increases from 0 meters/second to 30meters/second in 8 seconds. what is the average acceleration of the car?

One hazard of space travel is debris left by previous missions. there are several thousand masses large enough to detect by radar orbiting the earth, but there are far greater numbers of very small masses such as flakes of paint. calculate the force exerted by a 0.110 mg chip of paint that strikes a space shuttle window at a relative speed of 5.00 ✕ 103 m/s and sticks, given the collision lasts 6.00 ✕ 10-8 s. such a collision chipped the window of the ill-fated challenger in june 1983, causing $50,000 of damage.