Newton's Laws

A 20-ton truck collides with a 1500-lb car and causes a lot of damage to the car. (one ton is approximately 2000 lbs) Since a lot of damage is done on the car

the force on the truck is equal to the force on the car.

The cart of mass 10 kg shown below moves without frictional loss on a level table. A 10 N force pulls on the cart horizontally to the right. At the same time, a 30 N force at an angle of 60° above the horizontal pulls on the cart to the left. What is the magnitude of the horizontal acceleration of the cart?

.5

A child tugs on a rope attached to a 0.71 kg toy with a horizontal force of 17.5 N. A puppy pulls the toy in the opposite direction with a force 14 N. What is the acceleration of the toy?

4.9296

A rope of negligible mass supports a block that weighs 30 N. The breaking strength of the rope is 50 N. The largest acceleration that can be given to the block by pulling up on it with the rope without breaking the rope is most nearly

6.5 m/s/s

During a three-part circus stunt, a clown holds a ball. The clown then tosses the ball upward. After releasing it, the ball is caught a few moments later from above by another clown on a trapeze. Which set of data could represent the normal force exerted by the ground on the first clown during the stunt? The force due to gravity on the clown is 680 N and that on the ball is 20 N.

700 N, 705 N, 680 N

In interactions of action-reaction pairs involving Earth and everyday objects, the effect on Earth's motion is often negligible because

Earth has great inertia.

A block of mass M slides down a frictionless plane inclined at an angle θ with the horizontal. The normal force exerted by the plane on the block is

Mg cos θ

A batter strikes a baseball with a bat. Identify an action-reaction pair and describe the forces exerted by each.

The batter exerts a force on the bat; the bat exerts a force on the batter.

In which situation is the net force acting on a car zero?

The car maintains both its speed and direction.

A stone is thrown straight up. At the top of its path, the net force acting on it is

equal to its weight

A stone is thrown straight up. At the top of its path, the net force acting on it is

equal to its weight.

The change in the horizontal velocity of a 12-kg scooter is +0.5 m/s. What is the net horizontal force acting on it?

greater than 0 N