Answer:
If the track is horizontal and the string is pulled horizontally, the friction on the cart would be
.
Explanation:
Let
denote the mass of this cart, and let
denote the acceleration of this cart.
.
.
Apply Newton's Second Law to find the net force on this cart.
.
The following forces act upon this cart:
- (downward) gravitational attraction from the earth,
- (upward) normal force from the track,
- (forward) tension from the string, and
- (backward) friction from the track.
Assume that the track is horizontal, and that the string was pulled horizontally. The normal force from the track would exactly balance the downward gravitational attraction from the earth. Hence, the
net force on this cart would be equal (in size) to the size of the tension from the string (
) minus the size of the friction from the track.
In other words:
.
.
.
Here the block has two work done on it
1. Work done by gravity
2. Work done by friction force
So here it start from height "h" and then again raise to height hA after compressing the spring
So work done by the gravity is given as

Now work done by the friction force is to be calculated by finding total path length because friction force is a non conservative force and its work depends on total path


Total work done on it

So answer will be
None of these
The cart is at rest, so it is in equilibrium and there is no net force acting on it. The only forces acting on the cart are its weight (magnitude <em>w</em>), the normal force (mag. <em>n</em>), and the friction force (maximum mag. <em>f</em> ).
In the horizontal direction, we have
<em>n</em> cos(120º) + <em>f</em> cos(30º) = 0
-1/2 <em>n</em> + √3/2 <em>f</em> = 0
<em>n</em> = √3 <em>f</em>
and in the vertical,
<em>n</em> sin(120º) + <em>f</em> sin(30º) + (-<em>w</em>) = 0
<em>n</em> sin(120º) + <em>f</em> sin(30º) = (50 kg) (9.80 m/s²)
√3/2 <em>n</em> + 1/2 <em>f</em> = 490 N
Substitute <em>n</em> = √3 <em>f</em> and solve for <em>f</em> :
√3/2 (√3 <em>f </em>) + 1/2 <em>f</em> = 490 N
2 <em>f</em> = 490 N
<em>f</em> = 245 N
(pointed up the incline)
Answer:
2280 V
Explanation:
distance between the plates, d = 4 cm = 0.04 m
Electric field strength, E = 5.7 x 10^4 V/m
The formula for potential difference is given by
V = E x d
V = 5.7 x 10^4 x 0.04
V = 2280 V
thus, the potential difference between the plates is 2280 V.