# Search results

1. ### Speed of light questions

Homework Statement A signal (traveling at the speed of light) is sent from -4 ls (light seconds) towards a moving spaceship traveling at 0.866c. How long does it take for the signal to reach the ship? Homework Equations I'm pretty sure its t=(delta)D/c-v But I continue to get the...
2. ### Friction problem again Okay today is not my day

Homework Statement A passennger is standing without slipping in a forward accelerating train. The coeffeciant of the feet and the floor is 0.47. Determine the maximum required acceleration of the train relative to the track if the passenger is not to slip Homework Equations F=ma The...
3. ### Incline and Firction (again!)

Homework Statement A skier on a slope inclined at 4.7 degrees from the horizontal starts down the slope with an initial speed of 2.7m/s. The coefficient of friction is 0.11. Determine how far the skier will slide before coming to a rest. Homework Equations Fnet=ma F(f) = (mu)N The...
4. ### Simple but unsure, compound questions

A boy is pulling on a box at a 31 degree angle using 21N of force. The box remains stationary. The co-efficient of static friction is 0.55. What is the minimum mass? When I use the component method to solve this problem, do I need to calculate the mass for both the Horizontal and the Vertical...
5. ### FDB for TENNIS

Homework Statement for an FDB of an tennis ball hitting the racquet. Is the F(a)=F(n) or is F(a) larger then F(n). The Attempt at a Solution I think that F(a) = F(n). According to Newton's second law, they both receive the same force, however since the tennis ball has less mass...
6. ### Confusing (but surely simple) gravity problem

Homework Statement An exceptional vertical jump from rest would raise a person 0.80m off the ground. To do this, what constant force would a 70kg person have to exert against the ground? Assume the person lowers himself 0.20m prior to jumping and remains in a standing position while in the...
7. ### A falling man

[SOLVED] A falling man Homework Statement a 90kg man falls (freefalls) 10m, when he lands, his legs buckle and he goes down another 23cm. What was the average force he exerted on the ground? Homework Equations M = 90k a = 9.8 m/s^2 The Attempt at a Solution from freefall to...
8. ### Deriving F=ma? a vs F?

I knew i should have paid more attention in class =/ anyways, We have been studying newton's second law. And I have a question on my lab that asks for me to "derive equation for a (acceleration) vs F (force) and a (acceleration) vs m (mass)" a vs F and a vs M are two graphs which we did...