amanda

When jumping straight down, you can be seriously injured if you land stiff-legged. One way to avoid injury is to bend your knees upon landing to reduce the force of the impact. A 74.2-kg man just before contact with the ground has a speed of 8.89 m/s. (a) In a stiff-legged landing he comes to a halt in 2.74 ms. Find the magnitude of the average net force that acts on him during this time. (b) When he bends his knees, he comes to a halt in 0.119 s. Find the magnitude of the average net force now. (c) During the landing, the force of the ground on the man points upward, while the force due to gravity points downward. The average net force acting on the man includes both of these forces. Taking into account the directions of the forces, find the magnitude of the force applied by the ground on the man in part (b).

A 78.9-kg person, running horizontally with a velocity of +3.47 m/s, jumps onto a 10.5-kg sled that is initially at rest. (a) Ignoring the effects of friction during the collision, find the velocity of the sled and person as they move away. (b) The sled and person coast 30.0 m on level snow before coming to rest. What is the coefficient of kinetic friction between the sled and the snow?

I go the answer for a its 3.04m/s but i cannot figure out the anwer for b please help ?

When jumping straight down, you can be seriously injured if you land stiff-legged. One way to avoid injury is to bend your knees upon landing to reduce the force of the impact. A 74.2-kg man just before contact with the ground has a speed of 8.89 m/s. (a) In a stiff-legged landing he comes to a halt in 2.74 ms. Find the magnitude of the average net force that acts on him during this time. (b) When he bends his knees, he comes to a halt in 0.119 s. Find the magnitude of the average net force now. (c) During the landing, the force of the ground on the man points upward, while the force due to gravity points downward. The average net force acting on the man includes both of these forces. Taking into account the directions of the forces, find the magnitude of the force applied by the ground on the man in part (b).

Help cannot figure out!

p=uk(mh+psinfeta)/cosfeta

A small block of mass m = 2.00 kg is released, starting at rest, from a height h above the ground

on a ramp inclined at 45.0o (see figure below). The block reaches the bottom of the ramp and

enters a loop-the-loop of radius R = 1.20 m. There is no friction between the block and the

track. Treat the block as a point mass.

a) What is the speed of the block at position B if h = 8.50 m? (Notice: At position B, the

block is 2R above the ground.)

b) What is the magnitude of the normal force acting on the block when it is at position B,

the top of the loop, having started at the height h = 8.50 m? (Hint: Be sure to draw a

free-body diagram for the mass at position B.)

c) Find the minimum starting height, hmin, for which the block will just make it through the

loop without leaving the track at B. (Hint: When the block just makes it through the

loop, we set the normal force at B equal to zero, the critical condition, allowing us to

solve for the minimum speed at B. Once the minimum speed is found, we can determine

hmin using the work-energy theorem.)

I am having trouble with this as there are so many steps someone please help!

A 72.2-kg skier coasts up a snow-covered hill that makes an angle of 30.9 ° with the horizontal. The initial speed of the skier is 8.74 m/s. After coasting a distance of 1.91 m up the slope, the speed of the skier is 4.40 m/s. (a) Find the work done by the kinetic frictional force that acts on the skis. (b) What is the magnitude of the kinetic frictional force?

A skier starts from rest at the top of a hill. The skier coasts down the hill and up a second hill, as the drawing illustrates. The crest of the second hill is circular, with a radius of 29.5 m. Neglect friction and air resistance. What must be the height h of the first hill so that the skier just loses contact with the snow at the crest of the second hill?

I dont understand this because of the cicle at the end :s its like two different questions in one and i cant figure it out?

A pendulum consists of a small object hanging from the ceiling at the end of a string of negligible mass. The string has a length of 0.80 m. With the string hanging vertically, the object is given an initial velocity of 2.2 m/s parallel to the ground and swings upward in a circular arc. Eventually, the object comes to a momentary halt at a point where the string makes an angle θ with its initial vertical orientation and then swings back downward. Find the angle θ.

A “swing” ride at a carnival consists of chairs that are swung in a circle by 17.5 m long cables

attached to a vertical rotating pole, as the drawing shows. Note that the cables make an angle of

60.0o with respect to the vertical, as shown. Suppose the total mass of a chair and its occupant is

110 kg, treated as a point mass at the end of the cable.

Determine the tension in the cable attached to the chair.

Find the speed of the chair

Please help!!!

A 850-kg race car can drive around an unbanked turn at a maximum speed of 44 m/s without slipping. The turn has a radius of 200 m. Air flowing over the car's wing exerts a downward-pointing force (called the downforce) of 12000 N on the car. (a) What is the coefficient of static friction between the track and the car's tires? (b) What would be the maximum speed if no downforce acted on the car?

how do i do this step by step please help!

A “swing” ride at a carnival consists of chairs that are swung in a circle by 17.5 m long cables

attached to a vertical rotating pole, as the drawing shows. Note that the cables make an angle of

60.0o with respect to the vertical, as shown. Suppose the total mass of a chair and its occupant is

110 kg, treated as a point mass at the end of the cable.

(a) Determine the tension in the cable attached to the chair.

(b) Find the speed of the chair.

How do I do this step by step please help!

A block is pressed against a vertical wall by a force P, as the drawing shows.

This force can either push the block upward at a constant velocity or allow it to

slide downward at a constant velocity. The magnitude of the force is different in

the two cases, while the directional angle q is the same. Kinetic friction exists

between the block and the wall, and the coefficient of kinetic friction is 0.250. The

weight of the block is 39.0 N, and the directional angle for the force P is q = 30.0o.

Determine the magnitude of P when the block slides

(a) up the wall and

(b) down the wall.

Please help step by step!!

A mountain climber, in the process of crossing between two cliffs by a rope, pauses to rest. She weighs 550 N. As the drawing shows, she is closer to the left cliff than to the right cliff, with the result that the tensions in the left and right sides of the rope are not the same. Find the tensions in the rope to the left and to the right of the mountain climber.

The left angle is 65 and the right angle is 80

Please help me out step by step?

This force can either push the block upward at a constant velocity or allow it to slide downward at a constant velocity. The magnitude of the force is different in the two cases, while the directional angle θ is the same. Kinetic friction exists between the block and the wall, and the coefficient of kinetic friction is 0.340. The weight of the block is 45.0 N, and the directional angle for the force is θ = 37.0°. Determine the magnitude of when the block slides

(a) up the wall and

(b) down the wall.

Please help me step by step I dont get it ?

A block is pressed against a vertical wall by a force P, as the drawing shows.

This force can either push the block upward at a constant velocity or allow it to

slide downward at a constant velocity. The magnitude of the force is different in

the two cases, while the directional angle q is the same. Kinetic friction exists

between the block and the wall, and the coefficient of kinetic friction is 0.250. The

weight of the block is 39.0 N, and the directional angle for the force P is q = 30.0o.

Determine the magnitude of P when the block slides

(a) up the wall and

(b) down the wall.

The drawing (not to scale) shows one alignment of the sun, earth, and moon. The gravitational force that the sun exerts on the moon is perpendicular to the force that the earth exerts on the moon. The masses are: mass of sun=1.99 × 1030 kg, mass of earth=5.98 × 1024 kg, mass of moon=7.35 × 1022 kg. The distances shown in the drawing are rSM = 1.50 × 1011 m and rEM = 3.85 × 108 m. Determine the magnitude of the net gravitational force on the moon.

Please show me step by step if you can I dont understand this ?

This force can either push the block upward at a constant velocity or allow it to slide downward at a constant velocity. The magnitude of the force is different in the two cases, while the directional angle θ is the same. Kinetic friction exists between the block and the wall, and the coefficient of kinetic friction is 0.340. The weight of the block is 45.0 N, and the directional angle for the force is θ = 37.0°. Determine the magnitude of when the block slides

(a) up the wall and

(b) down the wall.

Please help me step by step I dont get it ?

A golfer, standing on a fairway, hits a shot to a green that is elevated 4.30 m above the point where she is standing. If the ball leaves her club with a velocity of 36.3 m/s at an angle of 30.3 ° above the ground, find the time that the ball is in the air before it hits the green.

A rocket is fired at a speed of 100 m/s from ground level, at an angle of 40.0 ° above the horizontal. The rocket is fired toward an 6.28-m high wall, which is located 15.0 m away. The rocket attains its launch speed in a negligibly short period of time, after which its engines shut down and the rocket coasts. By how much does the rocket clear the top of the wall?