Physics Answers

A Ferris wheel of radius 12m is turning about a horizontal axis through its center, such that the linear speed of a passenger on the rim is constant and equal to 9m/s.

a) What are the magnitude and direction of the acceleration of the passenger as he passes

through the lowest point in his circular motion?

A model of a helicopter rotor has four blades, each 3.40 m

long from the central shaft to the blade tip. The model is rotated in a wind tunnel at 550 rev/min (a) What is the linear speed of the blade tip, in (b) What is the radial acceleration of the blade tip expressed as a multiple of the acceleration of gravity, g?

A batter hits a baseball so that it leaves the bat with an initial speed 37.0 an initial angle 53.1o, at a location. Find

a) the position of the ball at t = 2.00 s.

b) the magnitude and direction of its velocity,

when t = 2.00 s.

c) the time when the ball reaches the highest point of its flight. d) its maximum height, h.

e) its horizontal range, 𝑅.

You are operating a remote-controlled model car on a vacant tennis court. Your position is the origin of coordinates, and the surface of the court lies in the 𝑥𝑦-plane. The car, which we represent as a point, has x- and y- coordinates that vary with time according to

 a) Find the car’s coordinates and its distance from you at time t = 2.0 s.

b) Find the car’s displacement and average velocity vectors during the interval from

t = 0 s to t = 2.0 s.

c) Find the components of the average acceleration in the interval from t = 0 s to t =

2.0 s.

In a 300-m race, runner A starts from rests and accelerates at 1.6m/s2 for the first 30 m and then runs at a constant speed. Runner B starts from rests and accelerates at 2.0m/s2 for the first 30m and then runs at a constant speed. Runner A begins running as soon as the race begins but B firsts takes a nap to rest up. What is the longest nap that B can take and still not to lose the race?

Switch S is closed to connect the uncharged capacitor of capacitance C=0.25mf to the battery of potential difference V=12V. The lower capacitor plate has thickness L= 0.5cm and face area A= 2*10–⁴, and it consist of copper, in which the density of conduction electrons is n= 8.49*10²⁸electrons/m³. From what depth d the plate must electrons move to the plate face as the capacitor becomes charged? a. A battery and capacitor circuit.

b. The lower capacitor plate

Switch S is closed to connect the uncharged capacitor of capacitance C=0.25mf to the battery of potential difference V=12V. The lower capacitor plate has thickness L= 0.5cm and face area A= 2*10–⁴, and it consist of copper, in which the density of conduction electrons is n= 8.49*10²⁸electrons/m³. From what depth d the plate must electrons move to the plate face as the capacitor becomes charged?

Kara Less was applying her makeup when she drove into South's busy parking lot last Friday morning. Unaware that Lisa Ford was stopped in her lane 30 feet ahead, Kara rear-ended Lisa's rented Taurus. Kara's 1300-kg car was moving at 11 m/s and stopped in 0.14 seconds. 3pts each

a. Determine the momentum change of Kara's car.

b. Determine the impulse experienced by Kara's car.,

c. Determine the magnitude of the force experienced by Kara's car.

Two protons are separated by a distance of 3.6×10^10 m in air

A. find the magnitude of the electric force once protons exerts on other. is the force attractive or repulsive?

B. find the magnitude of the gravitational force once proton is exerts on the other. is this force attractive or repulsive?

1.   One morning, while little Lenlen’s mother was busy in the kitchen, Little Lenlen rolls off the bed that is 0.50 m above the floor. If the floor is hardwood, little Lenlen’s head is brought to rest in approx. 2.0 mm. If the floor is carpeted, this stopping distance is increased to about 1.0 cm. Calculate the magnitude and duration of the acceleration in both cases, to determine the risk of injury. Assume that little Lenlen remains horizontal during the fall to the floor. (Note: A more complicated fall could result in a head velocity greater or less than the speed you calculate. Traumatic brain injury such as concussion results when the head undergoes a very large acceleration. Generally, an acceleration less than 800 m/s² lasting for any length of time will not cause injury, whereas an acceleration greater than 1000m/s² lasting for at least 1 ms will cause injury.)