Physics Answers

Two simple clutch disks of equal mass 6.3 kg are initially separate. They also have equal radii of R=0.55 m. One of the disks is accelerated to 5.7 rad/s in time Δt = 1.8 s. They are then brought in contact and both start to sping together. Calculate the angular velocity of the two disks together.

1. A clothes dryer at home has a power of 4, 500 watts and runs on a special 220 V household circuit. a) What is the current through the dryer? b) How many kilowatt-hours of electricity are used by the dryer if it is used for 4 hours in one week? 

 In the final stages of a moon landing, a lunar module descends under retro-thrust of its descent engine to a height of 𝑠 = 4 m above the lunar surface where it has a downward velocity of 4 m/s. Calculate the impact velocity with the moon’s surface if: The acceleration under the combined effect of gravity and retro-thrust is the following function of height 𝑎 = 𝑠/2.

A Ricocheting Bullet.

0.100-kg stone rests on a frictionless, horizontal surface. A bullet of mass 6.00 g, traveling

horizontally at 350 m/s, strikes the stone and rebounds horizontally at right angles to its original direction with a speed of 250

m/s.

(a)

Compute the magnitude and direction of the velocity of the stone after it is struck.

(b)

Is the collision perfectly elastic?

A 0.150-kg frame, when suspended from a coil spring, stretches the spring 0.050 m. A

0.200-kg lump of putty is dropped from rest onto the frame from a height of 30.0 cm (Fig.).

Find the maximum distance the frame moves downward from its initial position.

the

spring to

find the force constant

k

of the spring. Let

s

be the amount the spring is stretched.

A 0.150-kg frame, when suspended from a coil spring, stretches the spring 0.050 m. A

0.200-kg lump of putty is dropped from rest onto the frame from a height of 30.0 cm (Fig.).

Find the maximum distance the frame moves downward from its initial position.

the

spring to

find the force constant

k

of the spring. Let

s

be the amount the spring is stretched.

A spaceship is traveling at half the speed of light (0.5c). Their onboard clock shows that they traveled for a full year. How much time passed on Earth during their “year”? (Give your answer in years)

7. A ball is thrown vertically upward with a speed of 7.1 m/s. Find:

(9 points)

a. Maximum height reached the ball

b. Its time of flight

C. Velocity the ball would return to its starting point

An aircraft is moving horizontally with a speed of 60 m/s. At the height of 2 km, an object is dropped from the aircraft. Acceleration due to gravity = 9.8 m/s2, what is the time interval before the object hits the ground.

What is the gravitational potential energy of a 3 kg ball that is 1meter above the floor