Answer:
Explanation:
A physical quantity which can be completely described by the magnitude and direction both are called vector quantities. For example, displacement, velocity, etc.
A physical quantity which can be completely explained by the magnitude only is called scalar quantity. For example, mass, time, etc.
It is given that by using track and cart we can record the time and the distance travelled and also the speed of the cart can be recorded. With all this data we can solve questions on the laws of motion.
Like using the first law of motion we can determine the force of gravity acting on the cart that has moved a certain distance and the velocity or the speed of card has already been registered and since time is known putting the values in formula would help us calculate the gravitational pull acting on cart.
Answer:
The induced emf in the loop is 
Explanation:
Given that,
Length of the wire, L = 1.22 m
It changes its shape is changed from square to circular. Then the side of square be its circumference, 4a = L
4a = 1.22
a = 0.305 m
Area of square, 
Circumference of the loop,

Area of circle,

The induced emf is given by :

So, the induced emf in the loop is 
1.Density of the material building the raft must be lower than the water.
<span>2. Material must not react with water. </span>
<span>3.Material must have high strength. </span>
<span>4.Raft must be wide in-order to avoid drawing in the river.</span>