Answer:
4. It is the force of the road on the tires (an external force) that stops the car.
Explanation:
If there is no friction between the road and the tires, the car won't stop.
You can see this, for example, when there is ice on the road. You can still apply the brakes (internal force), but since there is no friction (external force) the car won't stop.
The force of the brakes on the wheels is not what makes the car stop, it is the friction of the road against still tires that makes it stop.
Water and baking soda can be used, too.
Answer:
(C) Only if it starts moving
Explanation:
We know that work done is given by
So there are two case in which work done is zero
First case is that when force and displacement are perpendicular to each other
And other case is that when there is no displacement
So for work to be done there must have displacement, if there is no displacement then there is no work done
So option (c) will be the correct option
Answer:
T = 25 N
Explanation:
The question says that "A 25 n block is suspended by a wire from the ceiling vitamin the tension that appears in the wire
?"
Weight of the block, W = 25 N
Weight of a body acts in downward direction and tension acts in upward direction. It would mean that,
Tension = weight of the block
T = mg
T = 25 N
Hence, the tension in the wire is 25 N.
