A 4 kg textbook sits on a desk. It is pushed horizontally with a 50 N applied force against a 15 N frictional force.
1 answer:
Answer:
b) No acceleration in the vertical
c) 35N
d) 35N
e)
Explanation:
a) The situation can be shown in the free body diagram shown in the figure below where F is the applied force, Fr is the friction force, W is the weight of the book and N is the normal force exerted vertically up from the desk to the book
b) The vertical movement is restrained by the normal force which opposes to the weight. In absence of any other force, they both are in equilibrium and the net force is zero
c) The net horizontal force acting on the book is the vectorial sum of the applied force and the friction force. Since they lie in the same axis and are opposed to each other:
d) The net force acting on the book is the vector sum of all forces in all axes. The normal and the weight cancel each other in the y-axis, so our resulting force is the x-axis net force, computed as above:
in the x-axis
e) Following Newton's second law, the acceleration is calculated as
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Answer:
Output power of the charger is 9.85 watts.
Explanation:
It is given that,
Output current of the USB charger, I = 1.97 A
The standard USB output voltage, V = 5 V
We need to find the output power of the charger. It can be determined using the following formula as :
P = V × I
P = 9.85 watts
The output power of the charger is 9.85 watts. Hence, this is the required solution.
To minimize neutron leakage from a reactor, the ratio of the surface area to the volume should be a minimum. For a given volume V the ratio of the sphere will be .
We know that the surface area and volume of the sphere is given by:
Therefore, the ratio between the surface area and the volume for the sphere will be:
Equating the volume to the constant c, we will find the value of .
Substituting the value of r in the ration between surface area and volume, we get:
Calculating the constants, we get:
Hence, the ration between surface area and volume is
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Answer:
False statement = There must be a non-zero net force acting on the object.
Explanation:
An object is moving at a constant speed along a straight line. If the speed is constant then its velocity must be constant. We know that the rate of change of velocity is called acceleration of the object i.e.
a = 0
⇒ The acceleration of the object is zero.
The product of force and acceleration gives the magnitude of force acting on the object i.e.
F = m a = 0
⇒ The net force acting on the object must be zero.
So, the option (a) is not true. This is because the force acting on the object is zero. First option contradicts the fact.