Answer: B. A magnet pulls a nail towards it
Explanation: Out of the list of answers, this is the only answer where a force is acting on an object. the act of the magnet pulling on the nail is the force, and the nail is the object.
At time 
seconds, the mass has angular speed
and hence linear speed
After 8 s, its linear speed is
and has centripetal acceleration with magnitude
To maintain this linear speed, by Newton's second law the required centripetal force should have magnitude
Answer: c) Positive acceleration describes an increase in speed; negative acceleration describes a decrease in speed.
Hey
On Earth, you can move or you can not move. if you are moving 50 mph that means relative to Earth (not the Andromeda galaxy). When you start moving (accelerating) you are now moving relative to Earth. when you start slowing down (decelerating [most scientists just say you have negative acceleration]) you are starting to match your velocity to Earth's velocity.
Hope it helped and made any sence at all.
Spiky bob your answerer.
Answer:
None
Explanation:
Force, F is given by ma where m is the mass of an object and a is acceleration
Acceleration is the rate of change in velocity per unit time. Since skaters with mass of 75 kg and 50 kg are moving at a constant speed, there is no acceleration hence F=50*0=0 and F=75*0=0
For skater of 45 kg, he is at rest to mean the initial and final velocitu of the skater is zero hence no acceleration, the force will be 45*0=0
Therefore, none of the skaters will experience a greater net force.
Answer:
t = 180 / 1.4 = 129 sec (time to swim horizontally across river)
S = 129 sec * V where V is speed of current and S is the distance he will be carried downstream
The problem does not specify V the speed of the river
