Friction/Newtons Law

A child slides down a slide with a 30° incline, and at the bottom her speed is precisely two-thirds what it would have been if the slide had been frictionless. Calculate the coefficient of kinetic friction between the slide and the child.

Dielectrics

A capacitor is made from two parallel plates, each with an area of 146 cm^2. The plates are separated by a distance of 0.58 mm. Half of the area within the plates is filled with paper and the other half is filled with air. Calculate the capacitance of this capacitor.

Question

For the last question I posted, the Key says the answer is 0.50 nF. How do they get that answer? P.S. I have Teflon being 2.1 and paper being 3.5

Work and Energy (Force - Catapult)

A 20,000 kg jet takes off from an aircraft carrier via a catapult. The jet's engines exert a constant force of 136 kN on the jet. The force exerted on the jet by the catapult is plotted in Fig. 7-24b (see attachment) with F1 = 1200 kN and F2 = 73 kN. (a) Determine the work done on the jet by its engines during the launch of th ...continues

Work & Energy

A(n) 81 g arrow is fired from a bow whose string exerts an average force of 105 N on the arrow over a distance of 72 cm. What is the speed of the arrow as it leaves the bow?

Work & Energy

A baseball (m = 145 g) traveling 55 m/s moves a fielder's glove backward 35 cm when the ball is caught. What was the average force exerted by the ball on the glove?

Work & Energy

An elevator cable breaks when a 715 kg elevator is 20.5 m above the top of a huge spring (k = 8.00 104 N/m) at the bottom of the shaft. (a) Calculate the work done by gravity on the elevator before it hits the spring. (b) Calculate the speed of the elevator just before striking the spring. (c) Calculate the amount the ...continues

Work & Energy

A softball having a mass of 0.25 kg is pitched at 114 km/h. By the time it reaches the plate, it may have slowed by 10 percent. Neglecting gravity, estimate the average force of air resistance during a pitch, if the distance between the plate and the pitcher is about 15 m.

Work & Energy

A 1200 kg car rolling on a horizontal surface has speed v = 66 km/h when it strikes a horizontal coiled spring and is brought to rest in a distance of 3.3 m. What is the spring constant of the spring?

Work & Energy

Assume that A = 9 i - 7 j, B = -8.0 i + 8.1 j + 4.2 k, and C = 6.8 i - 7.2 j. (a) Determine A · (B + C). (b) Determine (A + C) · B. (c) Determine (B + A) · C.