Answer with Explanation:
We are given that


a.We have to find the torque on the particle about the origin.
We know that
Torque=
By using the formula

b.



Substitute the values then we get



Because 

Answer:
100 newtons
Explanation:
Given,
Jamal pushing a large box by a force, F = 100 N
Work done on the large box is, W = 0
It is because the applied force is less than the force of the friction between the two surfaces.
Yet, there will be a force that is exerted by the large box on Jamal.
According to newton's third law of motion, every action has an equal and opposite reaction. The reaction force is in the direction opposite to the force of action. But, their magnitude remains the same.

Hence, If the action force is 100 N, then the reaction force should be in 100 N
Answer:
A massive object (like a galaxy cluster) bends the light from an object (like a quasar) that lies behind it.
Explanation:
A massive object, like a galaxy cluster, is able to deform the space-time shape as a consequence of its own gravity, so the light that it is coming from a source that is behind it in the line of sight will be bend or distorts in a way that will be magnified, making small arcs around the cluster with the image of the background object.
This technique is useful for astronomers since they make research of faraway objects (at hight redshift) that otherwise will difficult to detect with a telescope.
C. because the car traveled twice as long at the same rate as the truck