Mechanics | Relativity Answers

The large quadriceps muscle in the upper leg terminate at the lower end in a tendon attached to the upper end of the tibia. The forces on the lower leg are defined as: T is the tension in the tendon, w is the force of gravity acting on the lower leg, and F is the weight of the foot.
Find T when the tendon is at an angle of 25o with the tibia, assuming w=120N,F=20Nandthelegisextendedatanangleof40o with respect to the vertical. Assume that the center of gravity of the lower leg is at its center and that the tendon attaches to the lower leg at a point one fourth of the way down the leg

A particle moves along the X axis. Its position varies with time according to the function X(t) = 4t – 2t2, where X is in meters and t is in seconds.

1. Calculate the velocity of the particle V(t)
my answer was (0s,3s)????

2.) Calculate the acceleration of the particle a(t)
My answer was (-2,2s)???

3.) Calculate the velocity at t=2.5 s
dont get that one

4) Calculator the position at time t=3.5
dont get this either

thank you

Note: Students will solve this section and return it to teacher for checking.
1. Centre of gravity of rectangle is ___________
(a) it's center. (b) intersection of diagonals. (c) middle point of axis
2. A couple is formed by two _____ forces.
(a) like. (b)unlike. (c) Different
3. Centre of gravity of meter rod is ________
(a) center (b) intersection of diagonal. (c) intersection of medians
4. The torque produced in a body due to couple is equal to the product of one of the
force and________
(a)Couple. (b)Force. (c) Couple arm
5.When an object is resting in smooth horizontal surface it's weight is balanced by__
(a)Torque. (b)Reactional force (c) Couple
Q2: Write difference between couple and torque?
Q3: Find moment of couple produce by force of 50 N acting on two sides of stearing
wheel having radius of 20cm.

. An object moves along the x axis according to the equation x(t) (3.00t 2 2.00t  3.00) m, where t is in seconds. Determine (a) the average speed between t 2.00 s
and t 3.00 s, (b) the instantaneous speed at t 2.00 s
and at t 3.00 s, (c) the average acceleration between
t 2.00 s and t 3.00 s, and (d) the instantaneous acceleration at t 2.00 s and t 3.00 s.

Relativity question: Three objects, A, B, C, floating together in distant space side by side with internal clocks ticking in sync, a force is applied momentarily to B & C so that they accelerate away from A then travel away from A at some constant speed resulting in the clocks in B & C ticking slower than the clock in A. Now another force is momentarily applied to B in the opposite direction rendering B and A once again not moving in relation to one another while C continues to move away from B and A.
Will the clocks in B and A once again be in sync when they cease to move in relation to one another?
Will the clock in C tick slower than the clock in B after the force on B renders it stationary with respect to A?

A jet car can accelerate from stationary to 200ms-1 in 5.3 seconds. If its mass is 1200kg, calculate the average thrust it achieves during that time.

If kinetic energy of an object is been same at all times, how does momentum of that object works?

A 10n force acting on a certain mass increases its speed uniformly from 0 to 25 m/s in 5s. The magnitude of the mass in kg is?

suppose a uniform spherical star of mass M and radius R collapses to a uniform sphere of radius 10^-5 .If the original star had a rotation rate of 1 rev each 25 days(as does the sun) ,what will be the rotation rate of the resulting object

a car moving at 10m/s, accelerated uniformely over a distance of 25m, at the end of which the velocity of the car became 15m/s. determine the acceleration of the car and the time taken to cover the 25m