Mechanics | Relativity Answers

An upward force of 1:2x104 N acts on an elevator of mass 2:0x103 kg. Calculate the acceleration of the elevator. Take g = 9:8ms-2

A 40 N force applied at an angle of 37 degrees above the horizontal pulls a 5kg
box on a horizontal floor. The
acceleration of the box is 3m/s2 . How large a fritional force must be retarding the motion of the box?

A passenger in a moving car and a passerby standing at the road side see each other as moving in the opposite
direction. Which of the following is NOT true?
The passenger is in motion relative to the passerby
The passerby
is stationary relative to the passenger
Both observers are in motion relative to each other
The passerby
is in motion relative to the passenger

Which of the following statements is not correct about reference frames?
Laws of physics are invariant in inertial reference frames
In noninertial
reference frames the motion of objects depend only on the interactions of constituent particles among
themselves
Any reference frame moving at constant velocity with respect to an inerial reference frame is also inertial
If the coordinate axes of a reference frame attached to an object remain fixed in space then the object is at rest

What are the dimensions of power (time rate of change of expending energy)

The speed of 90 hm/hr is equal to m/
s

Two forces act on a point object as follows: 100 N at 170 and 100N at 50 . Find the resultant force

The resultant of vectors A~ and B has a magnitude of 20 units.A has a magnitude of 8 units, and the angle between A
and B is 40 . Calculate the magnitude of B

A man leaves the garrage in his house and drives to a neighbouring town which is twenty kilometres away from his house
on sightseeing.
He returns home to his garrage two hours after. What is his average velocity from home in km/h?

A monkey in a perch 20m high in a tree drops a coconut above the head of a zoo keeper as he runs with a speed 1.5m/s
beneath the tree. How far behind him in metres does the coconut hit the ground?