Mechanics | Relativity Answers

A 4 kg block is kept on a smooth frictionless surface. Another block of mass 2 kg is kept above this block. The coefficient of friction between the two blocks n = 0.5. If the lower block (4 kg block) is being pulled by 24 N force, find the force of friction acting between the two blocks.

A recovery vehicle is towing a broken down lorry, of mass 42 tonne, up an incline of 1 in 10. Both vehicles start from rest and accelerate constantly up the incline at 0.1m/s2. If the resistance to motion (not the gravitational component) is:-
F = 820 + 0.06V3 where F is resistance in Newtons and V is velocity in m/s. What is power in kW transmitted through the tow hook to the lorry at a velocity of 10m/s?
A. 462.82 B. 556.34 C. 67.65 D. 120.8 E. 1220.67

An object ejects 12% of its initial mass at time t = 0 along the negative x-axis. The ejected mass has a speed of 2.0 m/s. Shortly after, it ejects another 12% of its initial mass along the negative y-axis with the same speed.
(a) Assume the object started from rest and calculate the magnitude and direction of its final velocity.
magnitude m/s
direction ° counterclockwise from the +x-axis

(b) If the object started at an initial speed
v = (4.0 m/s, 6.0 m/s),
would the change in speed of the object be different than the change in speed in part (a)?
Yes
No

(c) If the object ejected 24% of its initial mass at time
t = 0
in the direction opposite to the direction found in part (a), what would be the magnitude and direction of its final velocity? (Assume the mass is ejected with a speed of 2.0 m/s and the object is initially at rest.)
magnitude m/s
direction ° counterclockwise from the +x-axis

(a) What is the magnitude of the force of gravity between Earth and Jupiter (take mass of Earth
ME = 6.00 1024 kg,
mass of Jupiter
MJ = 1.90 1027 kg,
and the distance between their centres
REJ = 5.89 108 m)?


(b) At what point between Earth and Jupiter is the net force of gravity on a body by both Earth and Jupiter exactly zero?

a body falls freely from the top of the tower.If covers 36% of the total height in last second before striking the ground level,the height of the tower is

A simple model rocket starts at rest, burns fuel to provide an acceleration of 2.5 m/s2. Once it reaches an altitude of 460 m the rocket runs out of fuel, its engine shuts off and it enters free-fall. Throughout we are neglecting air resistance and assume acceleration due to gravity is 9.8 m/s2.

(a) How long after being launched does the rocket run out of fuel?

(b) What is the velocity of the rocket when it runs out of fuel?

(c) What is the maximum height above the ground that the rocket reaches?

(d) What is the velocity of the rocket just before it crashes into the ground?

An ball rolls off a cliff 21.0 m above the ground with an initial horizontal speed of 5.0 m/s. Acceleration due to gravity is 9.8 m/s2.
a) How long after leaving the top of the cliff does the ball hit the ground?

b) How far from the base of the cliff does the ball land?

Take a hollow plastic ball (dia 3cm to 5cm) using a needle. Pass a thread of about 105 cm along a diameter of the ball.Tie a knot at one end. Hang the ball from a rigid support so that the ball is free to oscillate.Make a small hole (5mm dia) in the ball near the top.Fill it with sand and find its time period of oscillation. Empty the ball and fill it with steel balls/iron filings and repeat the experiment.Similarly carry out the experiment with common salt.compare the time periods obtained in the above three cases.What do you find? Explain your finding.

a hollow sphere and a solid sphere,both having the same mass of 5kg and radius 10m are initially at rest.if they are made to roll down on the same plane without slipping, the ratio of their speeds when they reach the bottom of the plane,vhollow/vsolid will be

what is acceleration